StrickrodtBM20183MStrickrodtHHBülthoffTMeilinger2018-09-00Epub aheadJournal of Experimental Psychology: Learning, Memory, and CognitionObjects learned within single enclosed spaces (e.g., rooms) can be represented within a single reference frame. Contrarily, the representation of navigable spaces (multiple interconnected enclosed spaces) is less well understood. In this study we examined different levels of integration within memory (local, regional, global), when learning object locations in navigable space. Participants consecutively learned two distinctive regions of a virtual environment that eventually converged at a common transition point and subsequently solved a pointing task. In Experiment 1 pointing latency increased with increasing corridor distance to the target and additionally when pointing into the other region. Further, when pointing within a region alignment with local and regional reference frames, when pointing across regional boundaries alignment with a global reference frame was found to accelerate pointing. Thus, participants memorized local corridors, clustered corridors into regions, and integrated globally across the entire environment. Introducing the transition point at the beginning of learning each region in Experiment 2 caused previous region effects to vanish. Our findings emphasize the importance of locally confined spaces for structuring spatial memory and suggest that the opportunity to integrate novel into existing spatial information early during learning may influence unit formation on the regional level. Further, global representations seem to be consulted only when accessing spatial information beyond regional borders. Our results are inconsistent with conceptions of spatial memory for large scale environments based either exclusively on local reference frames or upon a single reference frame encompassing the whole environment, but rather support hierarchical representation of space.nonotspecifiedhttp://www.cyberneum.de/published0Memory for navigable space is flexible and not restricted to exclusive local or global memory units1501715422WellerTWBM20183MWellerKTakahashiKWatanabeHHBülthoffTMeilinger2018-08-001374917Frontiers in PsychologyThe object orientation effect describes shorter perceived distances to the front than to the back of oriented objects. The present work extends previous studies in showing that the object orientation effect occurs not only for egocentric distances between an observer and an object, but also for exocentric distances, that are between two oriented objects. Participants watched animated virtual humans (avatars) which were either facing each other or looking away, and afterward adjusted a bar to estimate the perceived length. In two experiments, participants judged avatars facing each other as closer than avatars facing away from each other. As the judged distance was between two objects and did not involve the observer, results rule out an explanation that observers perceive object fronts as closer to prepare for future interaction with them. The second experiment tested an explanation by predictive coding, this is the extrapolation of the current state of affairs to likely future states here that avatars move forward. We used avatars standing on bridges either connecting them or running orthogonal to the inter-avatar line thus preventing forward movement. This variation of walkability did not influence participants’ judgments. We conclude that if predictive coding was used by participants, they did not consider the whole scene layout for prediction, but concentrated on avatars. Another potential explanation of the effect assumes a general asymmetrical distribution of inter-person distances: people facing each other might typically be closer to each other than when facing away and that this asymmetry is reflected as a bias in perception.nonotspecifiedhttp://www.cyberneum.de/published6The Object Orientation Effect in Exocentric Distances1501715422JanssenBKJC20183CPJanssenLNBoyleALKunWJuLChuang2018-07-00International Journal of Human-Computer InteractionWe introduce a Hidden Markov Model framework to formalize the beliefs that humans may have about the mode in which a semi-automated vehicle is operating. Previous research has identified various “levels of automation,” which serve to clarify the different degrees of a vehicle’s automation capabilities and expected operator involvement. However, a vehicle that is designed to perform at a certain level of
automation can actually operate across different modes of automation within its designated level, and its operational mode might also change over time. Confusion can arise when the user fails to understand the mode of automation that is in operation at any given time, and this potential for confusion is not captured in models that simply identify levels of automation. In contrast, the Hidden Markov Model
framework provides a systematic and formal specification of mode confusion due to incorrect user beliefs. The framework aligns with theory and practice in various interdisciplinary approaches to the field of vehicle automation. Therefore, it contributes to the principled design and evaluation of automated systems and future transportation systems.nonotspecifiedhttp://www.cyberneum.de/accepted0A Hidden Markov Framework to Capture Human-Machine Interaction in Automated Vehicles1501715422KhemlaniHJ2017_27SKhemlaniTHintereckerPNJohnson-LairdLondon, UK2017-07-0066366839th Annual Meeting of the Cognitive Science Society (CogSci 2017)People reason about possibilities routinely, and reasoners can infer “modal” conclusions, i.e., conclusions that concern what is possible or necessary, from premises that make no mention of modality. For instance, given that Cullen was born in New York or Kentucky, it is intuitive to infer that it’s possible that Cullen was born in New York, and a recent set of studies on modal reasoning bear out these intuitions (Hinterecker, Knauff, & Johnson-Laird, 2016). What explains the tendency to make modal inferences? Conventional logic does not apply to modal reasoning, and so logicians invented many alternative systems of modal logic to capture valid modal inferences. But, none of those systems can explain the inference above. We posit a novel theory based on the idea that reasoners build mental models, i.e., iconic simulations of possibilities, when they reason about sentential connectives such as and, if, and or (Johnson-Laird, 2006). The theory posits that reasoners represent a set of conjunctive possibilities to capture the meanings of compound assertions. It is implemented in a new computational process model of sentential reasoning that can draw modal conclusions from non-modal premises. We describe the theory and computational model, and show how its performance matches reasoners’ inferences in two studies by Hinterecker et al. (2016). We conclude by discussing the model-based theory in light of alternative accounts of reasoning.nonotspecifiedhttp://www.cyberneum.de/published5The provenance of modal inference1501715422Yuksel20171BYükselLogos VerlagBerlin, Germany2017-00-00Aerial robots, meaning robots with flying capabilities, are essentially robotic platforms, which are autonomously controlled via some sophisticated control engineering tools. Similar to aerial vehichles, they can overcome the gravitational forces thanks to their design and/or actuation type. What makes them different from the conventional aerial vehicles, is the level of their autonomy. Reducing the complexity for piloting of such robots/vehicles provide the human operator more freedom and comfort. With their increasing autonomy, they can perform many complicated tasks by their own (such as surveillance, monitoring, or inspection), leaving the human operator the most high-level decisions to be made, if necessary. In this way they can be operated in hazardous and challenging environments, which might posses high risks to the human health. Thanks to their wide range of usage, the ongoing researches on aerial robots is expected to have an increasing impact on the human life.
Aerial Physical Interaction (APhI) is a case, in which the aerial robot exerts meaningful forces and torques (wrench) to its environment while preserving its stable flight. In this case, the robot does not try avoiding every obstacle in its environment, but prepare itself for embracing the effect of a physical interaction, furthermore turn this interaction into some meaningful robotic tasks. Aerial manipulation can be considered as a subset of APhI, where the flying robot is designed and controlled in purpose of manipulating its environment. A clear motivation of using aerial robots for physical interaction, is to benefit their great workspace and agility. Moreover, developing robots that can perform not only APhI but also aerial manipulation can bring the great workspace of the flying robots together with the vast dexterity of the manipulating arms.
This thesis work is addressing the design, modeling and control problem of these aerial robots for the purpose of physical interaction and manipulation. Using the nonlinear mathematical models of the robots at hand, in this thesis several different control methods (IDA-PBC, Exact Linearization, Differential Flatness Based Control) for APhI and aerial manipulation tasks have been developed and proposed. Furthermore, novel design tools (e.g. new rigid/elastic manipulating arms, hardware, software) to be used together with miniature aerial robots are presented within this thesis, which contributes to the robotics society not only in terms of concrete theory but also practical implementation and experimental robotics.nonotspecifiedhttp://www.cyberneum.de/published219Design, Modeling and Control of Aerial Robots for Physical Interaction and Manipulation1501715422BulthoffWG20162HHBülthoffCWallravenMAGieseSpringerBerlin, Germany2016-00-0020952114Springer Handbook of Robotics: Part GRobots that share their environment with humans need to be able to recognize and manipulate objects and users, perform complex navigation tasks, and interpret and react to human emotional and communicative gestures. In all of these perceptual capabilities, the human brain, however, is still far ahead of robotic systems. Hence, taking clues from the way the human brain solves such complex perceptual tasks will help to design better robots. Similarly, once a robot interacts with humans, its behaviors and reactions will be judged by humans – movements of the robot, for example, should be fluid and graceful, and it should not evoke an eerie feeling when interacting with a user. In this chapter, we present Perceptual Robotics as the field of robotics that takes inspiration from perception research and neuroscience to, first, build better perceptual capabilities into robotic systems and, second, to validate the perceptual impact of robotic systems on the user.nonotspecifiedhttp://www.cyberneum.de/published19Perceptual Robotics1501715422StrickrodtM20157MStrickrodtTMeilingerCopenhagen, Denmark2015-11-093334Conference on Human Mobility, Cognition and GIScA vista space (VS), e.g., a room, is perceived from one vantage point, whereas an environmental space (ES), e.g., a building, is experienced successively during movement.
Participants learned the same object layout by walking through multiple corridors (ES) or within a differently oriented room (VS). In four VS conditions they either
learned a fully or a successively visible object layout, and either from a static position or by walking through the environment along a path, mirroring the translation in ES. Afterwards, participants pointed between object locations in different body orientations and reproduced the object layout. Pointing latency in ES increased with the number of corridors to the target and pointing performance was best along corridor-based orientations. In VS conditions latency did not increase with distance and pointing performance was best along room-based orientations, which were oblique
to corridor and walking orientations. Furthermore, ES learners arranged the layout in the order they experienced the objects, and less so VS learners. Most beneficial
pointing orientations, distance and order effects suggest that spatial memory in ES is qualitatively different from spatial memory in VS and that differences in the visible environment (spatial structure) rather than movement or successive presentation are responsible for that. Our results are in line with the dissociation of vista and environmental space as postulated by Montello (1993. Furthermore, our study provides a behavioral foundation for the application of isovists when conducting visual integration analysis, which is one module of the space syntax approach (e.g., Hillier, 1999).nonotspecifiedhttp://www.cyberneum.de/published1Movement, successive presentation and environmental structure and their influence on spatial memory in vista and
environmental space1501715422MasaratiQZYDPVS20137PMasaratiGQuarantaLZaichikYYashinPDesyatnikMDPavelJVenrooijHSmailiMoskva, Russia2015-10-0049750139th European Rotorcraft Forum (ERF 2013)nonotspecifiedhttp://www.cyberneum.de/published4Biodynamic Pilot Modelling for Aeroelastic A/RPC1501715422GeluardiNPB20137SGeluardiFNieuwenhuizenLPolliniHHBülthoffMoskva, Russia2015-10-0041943339th European Rotorcraft Forum (ERF 2013)At the Max Planck Institute for Biological Cybernetics the influence of an augmented system on helicopter pilots with limited flight skills is being investigated. This study would provide important contributions in the research field on personal air transport systems. In this project, the flight condition under study is the hover. The first step is the implementation of a rigid-body dynamic model. This could be used to perform handling qualities evaluations for comparing the pilot performances with and without augmented system. This paper aims to provide a lean procedure and a reliable measurement setup for the collection of the flight test data. The latter are necessary to identify the helicopter dynamic model. The mathematical and technical tools used to reach this purpose are described in detail. First, the measurement setup is presented, used to collect the piloted control inputs and the helicopter response. Second, a description of the flight maneuvers and the pilot
training phase is taken into consideration. Finally the flight test data collection is described and the results are
showed to assess and validate the setup and the procedure presented.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/ERF-2013-Geluardi.pdfpublished14Data Collection for Developing a Dynamic Model of a Light Helicopter1501715422FladBC2015_37NFladHHBülthoffLLChuangRostock, Germany2015-08-00115124International Summer School on Visual Computing (VCSS 2015)nonotspecifiedhttp://www.cyberneum.de/published9Combined use of eye-tracking and EEG to understand visual information processing1501715422KimCPCWBK20153JKimYGChungJ-YParkS-CChungCWallravenHHBülthoffS-PKim2015-06-00610117PLoS ONEPerceptual sensitivity to tactile roughness varies across individuals for the same degree of roughness. A number of neurophysiological studies have investigated the neural substrates of tactile roughness perception, but the neural processing underlying the strong individual differences in perceptual roughness sensitivity remains unknown. In this study, we explored the human brain activation patterns associated with the behavioral discriminability of surface texture roughness using functional magnetic resonance imaging (fMRI). First, a whole-brain searchlight multi-voxel pattern analysis (MVPA) was used to find brain regions from which we could decode roughness information. The searchlight MVPA revealed four brain regions showing significant decoding results: the supplementary motor area (SMA), contralateral postcentral gyrus (S1), and superior portion of the bilateral temporal pole (STP). Next, we evaluated the behavioral roughness discrimination sensitivity of each individual using the just-noticeable difference (JND) and correlated this with the decoding accuracy in each of the four regions. We found that only the SMA showed a significant correlation between neuronal decoding accuracy and JND across individuals; Participants with a smaller JND (i.e., better discrimination ability) exhibited higher decoding accuracy from their voxel response patterns in the SMA. Our findings suggest that multivariate voxel response patterns presented in the SMA represent individual perceptual sensitivity to tactile roughness and people with greater perceptual sensitivity to tactile roughness are likely to have more distinct neural representations of different roughness levels in their SMA.nonotspecifiedhttp://www.cyberneum.de/published16Decoding Accuracy in Supplementary Motor Cortex Correlates with Perceptual Sensitivity to Tactile Roughness1501715422Chang2014_27D-SChangHHBülthoffSde la RosaTübingen, Germany2014-06-006th International Conference on Brain and Cognitive Engineering (BCE 2014)nonotspecifiedhttp://www.cyberneum.de/published0Visual Adaptation to Social Actions: The Role of Meaning vs. Motion for Action Recognition1501715422Mohler201310BMohlerBulthoff2013_1010IBülthoffBulthoff2013_1110HHBülthoffMohlerRSS201328BMohlerBRaffinHSaitoOStaadtVenrooijPMvB20133JVenrooijMDPavelMMulderFCTvan der HelmHHBülthoff2013-12-0044421432CEAS Aeronautical JournalBiodynamic feedthrough (BDFT) occurs when vehicle accelerations feed through the pilot’s body and cause involuntary motions of limbs, resulting in involuntary control inputs. BDFT can severely reduce ride comfort, control accuracy and, above all, safety during the operation of rotorcraft. Furthermore, BDFT can cause and sustain rotorcraft-pilot couplings. Despite many different studies conducted in past decades—both within and outside of the rotorcraft community—BDFT is still a poorly understood phenomenon. The complexities involved in BDFT have kept researchers and manufacturers in the rotorcraft domain from developing robust ways of dealing with its effects. A practical BDFT pilot model, describing the amount of involuntary control inputs as a function of accelerations, could pave the way to account for adverse BDFT effects. In the current paper, such a model is proposed. Its structure is based on the model proposed by Mayo (15th European Rotorcraft Forum, Amsterdam, pp. 81-001–81-012 1989), and its accuracy and usability are improved by incorporating insights from recently obtained experimental data. An evaluation of the model performance shows that the model describes the measured data well and that it provides a considerable improvement to the original Mayo model. Furthermore, the results indicate that the neuromuscular dynamics have an important influence on the BDFT model parameters.nonotspecifiedhttp://www.cyberneum.de/published11A practical biodynamic feedthrough model for helicopters1501715422WallravenH20133CHerdtweckCWallraven2013-12-00128114PLoS ONEWe present three experiments on horizon estimation. In Experiment 1 we verify the human ability to estimate the horizon in static images from only visual input. Estimates are given without time constraints with emphasis on precision. The resulting estimates are used as baseline to evaluate horizon estimates from early visual processes. Stimuli are presented for only ms and then masked to purge visual short-term memory and enforcing estimates to rely on early processes, only. The high agreement between estimates and the lack of a training effect shows that enough information about viewpoint is extracted in the first few hundred milliseconds to make accurate horizon estimation possible. In Experiment 3 we investigate several strategies to estimate the horizon in the computer and compare human with machine “behavior” for different image manipulations and image scene types.nonotspecifiedhttp://www.cyberneum.de/published13Estimation of the Horizon in Photographed Outdoor Scenes by Human and Machine1501715422DropPDVM20123FMDropDMPoolHJDamveldMMvan PaassenMMulder2013-12-0064319361949IEEE Transactions on CyberneticsIn the manual control of a dynamic system, the human controller (HC) often follows a visible and predictable reference path. Compared with a purely feedback control strategy, performance can be improved by making use of this knowledge of the reference. The operator could effectively introduce feedforward control in conjunction with a feedback path to compensate for errors, as hypothesized in literature. However, feedforward behavior has never been identified from experimental data, nor have the hypothesized models been validated. This paper investigates human control behavior in pursuit tracking of a predictable reference signal while being perturbed by a quasi-random multisine disturbance signal. An experiment was done in which the relative strength of the target and disturbance signals were systematically varied. The anticipated changes in control behavior were studied by means of an ARX model analysis and by fitting three parametric HC models: two different feedback models and a combined feedforward and feedback model. The ARX analysis shows that the experiment participants employed control action on both the error and the target signal. The control action on the target was similar to the inverse of the system dynamics. Model fits show that this behavior can be modeled best by the combined feedforward and feedback model.nonotspecifiedhttp://www.cyberneum.de/published13Identification of the Feedforward Component of Manual Control in Tasks with Predictable Target Signals1501715422MichelRBHV20133CMichelBRossionIBülthoffWGHaywardQCVuong2013-12-009-102112021223Visual CognitionFaces from another race are generally more difficult to recognize than faces from one's own race. However, faces provide multiple cues for recognition and it remains unknown what are the relative contribution of these cues to this “other-race effect”. In the current study, we used three-dimensional laser-scanned head models which allowed us to independently manipulate two prominent cues for face recognition: the facial shape morphology and the facial surface properties (texture and colour). In Experiment 1, Asian and Caucasian participants implicitly learned a set of Asian and Caucasian faces that had both shape and surface cues to facial identity. Their recognition of these encoded faces was then tested in an old/new recognition task. For these face stimuli, we found a robust other-race effect: Both groups were more accurate at recognizing own-race than other-race faces. Having established the other-race effect, in Experiment 2 we provided only shape cues for recognition and in Experiment 3 we provided only surface cues for recognition. Caucasian participants continued to show the other-race effect when only shape information was available, whereas Asian participants showed no effect. When only surface information was available, there was a weak pattern for the other-race effect in Asians. Performance was poor in this latter experiment, so this pattern needs to be interpreted with caution. Overall, these findings suggest that Asian and Caucasian participants rely differently on shape and surface cues to recognize own-race faces, and that they continue to use the same cues for other-race faces, which may be suboptimal for these faces.nonotspecifiedhttp://www.cyberneum.de/published21The contribution of shape and surface information in the other-race face effect1501715422Dobrickid20133MDobrickiSde la Rosa2013-12-0012819PLoS ONEPrevious research suggests that bodily self-identification, bodily self-localization, agency, and the sense of being present in space are critical aspects of conscious full-body self-perception. However, none of the existing studies have investigated the relationship of these aspects to each other, i.e., whether they can be identified to be distinguishable components of the structure of conscious full-body self-perception. Therefore, the objective of the present investigation is to elucidate the structure of conscious full-body self-perception. We performed two studies in which we stroked the back of healthy individuals for three minutes while they watched the back of a distant virtual body being synchronously stroked with a virtual stick. After visuo-tactile stimulation, participants assessed changes in their bodily self-perception with a custom made self-report questionnaire. In the first study, we investigated the structure of conscious full-body self-perception by analyzing the responses to the questionnaire by means of multidimensional scaling combined with cluster analysis. In the second study, we then extended the questionnaire and validated the stability of the structure of conscious full-body self-perception found in the first study within a larger sample of individuals by performing a principle components analysis of the questionnaire responses. The results of the two studies converge in suggesting that the structure of conscious full-body self-perception consists of the following three distinct components: bodily self-identification, space-related self-perception (spatial presence), and agency.nonotspecifiedhttp://www.cyberneum.de/published8The structure of conscious bodily self-perception during full-body illusions1501715422HeydrichDAHBMB2013_23LHeydrichTJDoddsJEAspellBHerbelinHHBülthoffBJMohlerOBlanke2013-12-009464115Frontiers in PsychologyIn neurology and psychiatry the detailed study of illusory own body perceptions has suggested close links between bodily processing and self-consciousness. One such illusory own body perception is heautoscopy where patients have the sensation of being reduplicated and to exist at two or even more locations. In previous experiments, using a video head-mounted display, self-location and self-identification were manipulated by applying conflicting visuo-tactile information. Yet the experienced singularity of the self was not affected, i.e., participants did not experience having multiple bodies or selves. In two experiments presented in this paper, we investigated self-location and self-identification while participants saw two virtual bodies (video-generated in study 1 and 3D computer generated in study 2) that were stroked either synchronously or asynchronously with their own body. In both experiments, we report that self-identification with two virtual bodies was stronger during synchronous stroking. Furthermore, in the video generated setup with synchronous stroking participants reported a greater feeling of having multiple bodies than in the control conditions. In study 1, but not in study 2, we report that self-location – measured by anterior posterior drift – was significantly shifted towards the two bodies in the synchronous condition only. Self-identification with two bodies, the sensation of having multiple bodies, and the changes in self-location show that the experienced singularity of the self can be studied experimentally. We discuss our data with respect to ownership for supernumerary hands and heautoscopy. We finally compare the effects of the video and 3D computer generated head-mounted display technology and discuss the possible benefits of using either technology to induce changes in illusory self-identification with a virtual body.nonotspecifiedhttp://www.cyberneum.de/published14Visual capture and the experience of having two bodies: evidence from two different virtual reality techniques1501715422PariseS2012_22CVPariseCSpenceOxford University PressOxford, UK2013-12-00790815Oxford Handbook of SynesthesiaFor more than a century now, researchers have acknowledged the existence of seemingly arbitrary crossmodal congruency effects between dimensions of sensory stimuli in the general (i.e., non-synesthetic) population. Such phenomena, known by a variety of terms including 'crossmodal correspondences', involve individual stimulus properties, rely on a crossmodal mapping of unisensory features, and appear to be shared by the majority of individuals. In other words, members of the general population share underlying preferences for specific pairings across the senses (e.g., preferring certain shapes to accompany certain sounds). Crossmodal correspondences between complementary sensory cues have often been referred to as synesthetic correspondences but, we would argue, differ from full-blown synesthetic experiences in a number of important ways, including the fact that there are no idiosyncratic concurrent sensations. Recent psychophysical evidence suggests that such crossmodal correspondences can modulate multisensory integration by helping to resolve the crossmodal binding problem. Here, we propose a model to account for the effects of crossmodal correspondences between complementary auditory and visual cues and critically review their relation to full-blown synesthesia.nonotspecifiedhttp://www.cyberneum.de/published25Audiovisual Cross-Modal Correspondences in the General Population15017154221501718824Franchi2013_910AFranchiGeussDS201310MNGeussFDDu ToitJKStefanucciChang201310D-SChangZhaoB2013_310MZhaoIBülthoffFranchi2013_510AFranchiLeitaoTN20137JLeitãoAThielscherUNoppeneySan Diego, CA, USA2013-11-1243rd Annual Meeting of the Society for Neuroscience (Neuroscience 2013)Visuospatial attention is essential for successful interactions with the environment. It has been shown that visuospatial attention is based on a right lateralized network of parietal and frontal areas. Indeed, insights about this network arise from studies with visual neglect patients, who after a localized lesion in right parietal or temporal areas fail to perceive or attend normally to signals in the contralateral left visual hemifield. Accumulating evidence shows that transcranial magnetic stimulation (TMS) over the parietal cortex is able to induce neglect-like changes in performance during visuopatial tasks. At the neural level, parietal TMS has also been shown to modulate activity in remote interconnected areas of the brain, in particular in the occipito-temporal cortex. This study used concurrent TMS-fMRI to investigate the role of the right intraparietal sulcus (IPS) in visual detection under spatial attention. Participants performed a visual target detection task during TMS-stimulation to the right anterior IPS and Sham-TMS-stimulation where specific TMS effects were abolished by placing a 2cm thick plastic plate between the TMS-coil and the participant’s head. In both conditions, TMS was applied in bursts of 4 pulses (10Hz), starting 90ms after the target onset. Participants fixated on a cross in the centre of the screen and attended to a location indicated by a placeholder in the left lower visual field. On each trial, they indicated whether they detected a small visual stimulus that was presented inside the placeholder on 50% of the trials. Blocks of 12 trials were interleaved with baseline periods of 13s. Hence, attention was sustained specifically to the left visual field throughout the entire block relative to baseline. As expected, compared to baseline, attended periods activated the network of fronto-parietal areas commonly involved in attention. Critically, IPS-TMS relative to Sham-TMS significantly decreased the difference in activations between visual present and visual absent trials by reducing the deactivations during visual present trials in the right anterior fusiform gyrus, an area that has previously been reported to be modulated by attention. Our results show that the right human parietal cortex influences visual processing in the right ipsilateral occipital cortex by modulating stimulus evoked (de)activations during spatial attention.nonotspecifiedhttp://www.cyberneum.de/published0Influences of right parietal cortex in the visual processing of contralateral visual stimuli in a sustained attentional context150171542215017188261501718821RemiN20137RGauUNoppeneySan Diego, CA, USA2013-11-1243rd Annual Meeting of the Society for Neuroscience (Neuroscience 2013)In the natural environment our senses are bombarded with many different signals. To form a coherent percept, the brain should integrate signals originating from a common source and segregate signals from different sources. This psychophysics-fMRI study investigated how the human brain combines bottom-up inputs (i.e. congruent VS incongruent signals) and top-down prior predictions (i.e. common source prior) to infer whether sensory signals should be integrated or segregated.
Sixteen participants were shown audio-visual movies of congruent (e.g. visual «Ti» with auditory /Ti/), incongruent (e.g. visual «Ti» with auditory /Pi/) and McGurk syllables (e.g. visual «Ki» with auditory /Pi/, which can be fused into the illusionary percept “Ti”). Critically, we manipulated participants’ top-down predictions (i.e. common source prior) by presenting the McGurk stimuli in a series of congruent or incongruent syllables. On each trial, participants reported their syllable percept in forced choice procedure with 6 response options.
At the behavioural level, participants were more likely to fuse auditory and visual signals of a McGurk trial into an illusionary percept in congruent relative to incongruent contexts. This response profile indicates that participant’s prior top-down predictions (i.e. common source prior) influence whether or not they integrate sensory signals into a coherent percept.
At the neural level, incongruent relative to congruent bottom-up inputs increased activations in a widespread left-lateralised fronto-parietal network. The left prefrontal activations also increased for McGurk trials, when participants selectively reported their auditory percept and did not fuse auditory and visual McGurk signals into a unified percept. Critically, this effect was enhanced for incongruent contexts when participants expected that sensory signals are incongruent and needed to be segregated.
Collectively, our results demonstrate that the left inferior frontal sulcus determines whether sensory signals should be integrated or segregated by combining (i) top-down predictions generated from prior incongruent trials with (ii) bottom-up information about sensory conflict in the incoming signals. Furthermore, it exerts top-down control that enables participants to process sensory signals independently and selectively report their percept in one sensory (i.e. here auditory) modality.nonotspecifiedhttp://www.cyberneum.de/published0The left prefrontal cortex controls information integration by combining bottom-up inputs and top-down predictions15017188261501715422Franchi2013_610AFranchiMeilinger201310TMeilingerRoheN2013_27TRoheUNoppeneySan Diego, CA, USA2013-11-1143rd Annual Meeting of the Society for Neuroscience (Neuroscience 2013)To form an accurate percept of the environment the brain integrates sensory signals weighted by their relative reliabilities (Ernst and Banks, 2002). Indeed, recent neurophysiological research has demonstrated that activity of multisensory MSTd neurons during a heading task is modulated by changes in cue reliability in line with predictions of optimal integration (Fetsch et al., 2012). Moreover, top-down influences like task-relevance modulate multisensory perception (Bertelson and Radeau, 1981). The current study investigated how the human brain integrates audiovisual signals into spatial representations depending on their relative reliability and task-relevance. Using fMRI, we characterized how these integration processes emerged along the visual and auditory processing hierarchies. Subjects (N = 5) were presented with synchronous audiovisual signals that were spatially congruent or discrepant at 4 positions along the azimuth. We manipulated visual reliability (low vs. high) and task-relevance (auditory vs. visual-selective localization). Multivariate decoding of spatial information from fMRI data revealed that multisensory influences on spatial representations were present already at the primary cortical level and progressively increased along the cortical hierarchies. Likewise, the influence of task-relevance increased. Most prominently, the intraparietal sulcus integrated audiovisual signals weighted by their relative reliabilities and task-relevance. Further, IPS showed the greatest correlation with participant’s behavioral crossmodal bias. Collectively, the results suggest that IPS forms a spatial priority map (Bisley and Goldberg, 2010) by integrating sensory signals weighted by their bottom-up reliability and top-down task-relevance.nonotspecifiedhttp://www.cyberneum.de/published0Intraparietal sulcus forms multisensory spatial priority maps15017154221501718826Bulthoff2013_910HHBülthoffDobsSBG20137KDobsJSchultzIBülthoffJLGardnerSan Diego, CA, USA2013-11-1043rd Annual Meeting of the Society for Neuroscience (Neuroscience 2013)Identity and facial expression of faces we interact with are represented as invariant and changeable aspects, respectively - what are the cortical mechanisms that allow us to selectively extract information about these two important cues? We had subjects attend to either identity or expression of the same dynamic face stimuli and decoded concurrently measured fMRI activity to ask whether distinct cortical areas were differentially engaged in these tasks.
We measured fMRI activity (3x3x3mm, 34 slices, TR=1.5, 4T) from 6 human subjects (2 female) as they performed a change-detection task on dynamic face stimuli. At trial onset, a cue (letters ‘E’ or ‘I’) was presented (0.5s) which instructed subjects to attend to either the expression or the identity of animations of faces (8 presentations per trial of 2s movie clips depicting 1 of 2 facial identities expressing happiness or anger). Subjects were to report (by button press) changes in the cued dimension (these occurred in 20% of trials) and ignore changes in the uncued dimension. Subjects successfully attended to the cued dimension (mean d’=2.4 for cued and d’=-1.9 for uncued dimension), and sensitivity did not differ across tasks (F(1,10)=0.19, p>0.6). Subjects performed 18-20 7min scans (20 trials/scan in pseudorandom order) in 2 sessions.
We built linear classifiers to decode the attended dimension. Face-sensitive areas were defined in separate localizer scans as clusters of voxels responding more to faces than to houses. To independently determine the voxels to be included in the analyses, we ran a task localizer in which 10s grey screen was alternated with 10s of stimuli+task. For each area, we selected the 100 voxels whose signal correlated best with task/no task alternations. BOLD signal in these voxels was averaged over 3-21s of each trial of the main experiment, concatenated across subjects and sessions and used to build the classifiers.
We found that we could decode the attended dimension on cross-validated data from many visual cortical areas (percentage correct classifications: FFA: 68%, MT: 73%, OFA: 79%, STS: 68%, V1: 77%; p<0.05, permutation test). However, while ventral face-sensitive areas (OFA, FFA) showed larger BOLD signal during attention-to-identity than attention-to-expression trials (p<0.001, t-test), motion processing areas (MT, STS) showed the opposite effect (p<0.001, t-test). Our results suggest that attending to expression or identity engages areas involved in stimulus-specific processing of these two dimensions. Moreover, attending to expression encoded in facial motion recruits motion processing areas, while attending to face identity activates ventral face-sensitive areas.nonotspecifiedhttp://www.cyberneum.de/published0Attending to expression or identity of dynamic faces engages different cortical areas1501715422FranchiSBB20137AFranchiPStegagnoMBasileHHBülthoffTokyo, Japan2013-11-0714IEEE/RSJ IROS'13 International Workshop on Vision-based Closed-Loop Control and Navigation of Micro Helicopters in GPS-denied EnvironmentsThis talk will present the design of a platform for autonomous navigation of a quadrotor UAV based on RGB-D technology. The proposed platform can safely navigate in an unknown environment while self-stabilization is done relying only on its own sensor perception. An estimation system based IMU and RGB-D integration computes the velocity of the quadrotor in its body frame. Experimental tests conducted as teleoperation experiments show the effectiveness of our approach in an unstructured environment.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/IROS-2013-Workshop-Franchi.pdfpublished3RGB-D based Haptic Teleoperation of UAVs with Onboard Sensors: Development and Preliminary Results1501715422Zhao201310MZhaoIBülthoffFranchi2013_77AFranchiTokyo, Japan2013-11-0314IEEE/RSJ IROS'13 Workshop: From Remotely Controlled to Autonomous-Collaborative RobotsThis talk will provide a high-level overview of some of
the very recent and current activities of the Autonomous
Robotics and Human-Machine Systems group at the MPI for
Biological Cybernetics. The talk will also give a perspective about future challenges in the aerial collaborative robotics and haptic teleoperation field, with particular emphasis on onboard state estimation and physical interaction capabilities.
The main research activities of the group are centered
around the study and design of autonomous robotic systems
evolving in an uncertain and dynamical world and interacting
with people, and from a control-oriented perspective. The
group activity can be divided into two main areas:
Algorithms for collaborative autonomous control Algorithms for human interaction through interfaces.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/IROS-2013-WorkRCtoACR-Franchi.pdfpublished3Towards Autonomous-collaborative and Haptic-tele-operated UAVs with Fully-onboard State Estimation and Physical Interaction Capabilities1501715422deWinkelSBBGW20133KNde WinkelFSoykaMBarnett-CowanHHBülthoffELGroenPJWerkhoven2013-11-002231209218Experimental Brain ResearchThe brain is able to determine angular self-motion from visual, vestibular, and kinesthetic information. There is compelling evidence that both humans and non-human primates integrate visual and inertial (i.e., vestibular and kinesthetic) information in a statistically optimal fashion when discriminating heading direction. In the present study, we investigated whether the brain also integrates information about angular self-motion in a similar manner. Eight participants performed a 2IFC task in which they discriminated yaw-rotations (2-s sinusoidal acceleration) on peak velocity. Just-noticeable differences (JNDs) were determined as a measure of precision in unimodal inertial-only and visual-only trials, as well as in bimodal visual–inertial trials. The visual stimulus was a moving stripe pattern, synchronized with the inertial motion. Peak velocity of comparison stimuli was varied relative to the standard stimulus. Individual analyses showed that data of three participants showed an increase in bimodal precision, consistent with the optimal integration model; while data from the other participants did not conform to maximum-likelihood integration schemes. We suggest that either the sensory cues were not perceived as congruent, that integration might be achieved with fixed weights, or that estimates of visual precision obtained from non-moving observers do not accurately reflect visual precision during self-motion.nonotspecifiedhttp://www.cyberneum.de/published9Integration of visual and inertial cues in the perception of angular self-motion1501715422GrabeBR20137VGrabeHHBülthoffPRobuffo GiordanoTokyo, Japan2013-11-0051935200IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2013)For the purpose of autonomous UAV flight control, cameras are ubiquitously exploited as a cheap and effective onboard sensor for obtaining non-metric position or velocity measurements. Since the metric scale cannot be directly re- covered from visual input only, several methods have been proposed in the recent literature to overcome this limitation by exploiting independent "metric" information from additional onboard sensors. The flexibility of most approaches is, however, often limited by the need of constantly tracking over time a certain set of features in the environment, thus potentially suffering from possible occlusions or loss of tracking during flight. In this respect, in this paper we address the problem of estimating the scale of the observed linear velocity in the UAV body frame from direct measurement of the instantaneous (and non-metric) optical flow, and the integration of an on- board Inertial Measurement Unit (IMU) for providing (metric) acceleration readings. To this end, two different estimation techniques are developed and critically compared: a standard Extended Kalman Filter (EKF) and a novel nonlinear observer stemming from the adaptive control literature. Results based on simulated and real data recorded during a quadrotor UAV flight demonstrate the effectiveness of the approach.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/IROS-2013-Grabe-Preprint.pdfpublished7A comparison of scale estimation schemes for a quadrotor UAV based on optical flow and IMU measurements1501715422SpicaRRBF20137RSpicaPRobuffo GiordanoMRyllHHBülthoffAFranchiCompiegne, France2013-11-001982052nd Workshop on Research, Education and Development of Unmanned Aerial Systems (RED-UAS 2013)In this paper, we illustrate an open-source ready-to-use hardware/software architecture for a quadrotor UAV. The presented platform is price effective, highly customizable, and easily exploitable by other researchers involved in high-level UAV control tasks and for educational purposes as well. The use of object-oriented programming and full support of Robot Operating System (ROS) and Matlab Simulink allows for an efficient customization, code reuse, functionality expansion and rapid prototyping of new algorithms. We provide an extensive illustration of the various UAV components, a thorough description of the main basic algorithms and calibration procedures, and finally present some experimental case studies aimed at showing the effectiveness of the proposed architecture.nonotspecifiedhttp://www.cyberneum.de/published7An Open-Source Hardware/Software Architecture for Quadrotor UAVs1501715422AntonelliCRCF20137GAntonelliECataldiPRobuffo GiordanoSChiaveriniAFranchiTokyo, Japan2013-11-0024392444IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2013)In this paper, an adaptive trajectory tracking controller for quadrotor MAVs is presented. The controller exploits the common assumption of a faster orientation dy- namics w.r.t. the translational one, and is able to asymptotically compensate for parametric uncertainties (e.g., displaced center of mass), as well as external disturbances (e.g., wind). The good performance of the proposed controller is then demonstrated by means of an extensive experimental evaluation performed with a commercially-available quadrotor MAV.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/2013k-AntCatRobChiFra-preprint.pdfpublished5Experimental validation of a new adaptive control scheme for quadrotors MAVs1501715422NieuwenhuizenCB20137FMNieuwenhuizenLLChuangHHBülthoffFrankfurt a.M., Germany2013-11-00135. Internationale HELI World Konferenz "HELICOPTER Technologies", "HELICOPTER Operations" at the International Aerospace Supply Fair AIRTEC 2013Current means of transportation for daily commuting are reaching their limits during peak travel times, which results in waste of fuel and loss of time and money. A recent study commissioned by the European Union considers a personal aerial transportation system (PATS) as a viable alternative for transportation to and from work. It also acknowledges that developing such a transportation system should not focus on designing a new flying vehicle for personal use, but instead on investigating issues surrounding the implementation of the transportation system itself. This is the aim of European project myCopter: to determine the social and technological aspects needed to set up a transportation system based on personal aerial vehicles (PAVs). The project focuses on three research areas: human-machine interfaces and training, automation technologies, and social acceptance.
Our extended abstract for inclusion in the conference proceedings and our presentation will focus on the achievements during the first 2.5 years of the 4-year project. These include the development of an augmented dynamic model of a PAV with excellent handling qualities that are suitable for training purposes. The training requirements for novice pilots are currently under development. Experimental evaluations on haptic guidance and human-in-the-loop control tasks have allowed us to start implementing a haptic Highway-in-the-Sky display to support novice pilots and to investigate metrics for objectively determining workload using psychophysiological measurements.
Within the project, developments for automation technologies have focused on vision-based algorithms. We have integrated such algorithms in the control and navigation architecture of unmanned aerial vehicles (UAVs). Detecting suitable landing spots from monocular camera images recorded in flight has proven to reliably work off-line, but further work is required to be able to use this approach in real time. Furthermore, we have built multiple low-cost UAVs and equipped them with radar sensors to test collision avoidance strategies in real flight. Such algorithms are currently under development and will take inspiration from crowd simulations.
Finally, using technology assessment methodologies, we have assessed potential markets for PAVs and challenges for its integration into the current transportation system. This will lead to structured discussions on expectations and requirements of potential PAV users.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/HeliWorld-2013-Nieuwenhuizen.pdfpublished2myCopter: Enabling Technologies for Personal Aerial Transportation Systems: Project status after 2.5 years1501715422StegagnoBBF20137PStegagnoMBasileHHBülthoffAFranchiCompiegne, France2013-11-0087922nd Workshop on Research, Education and Development of Unmanned Aerial Systems (RED-UAS 2013)In this paper we present the design of a platform for autonomous navigation of a quadrotor UAV based on RGB-D technology. The proposed platform can safely navigate
in an unknown environment while self-stabilization is done relying only on its own sensor perception. We developed an estimation system based on the integration of IMU and RGB-D
measurements in order to estimate the velocity of the quadrotor in its body frame. Experimental tests conducted as teleoperation experiments show the effectiveness of our approach in an unstructured environment.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/2013p-SteBasBueFra-preprint.pdfpublished5Vision-based Autonomous Control of a Quadrotor UAV using an Onboard RGB-D Camera and its Application to Haptic Teleoperation1501715422Franchi2013_810AFranchiEsins201310JEsinsBieg201310H-JBiegRedcayDMKPTGS20133ERedcayDDodell-FederPLMavrosMKleinerMJPearrowCTriantafyllouJDGabrieliRSaxe2013-10-0010342511–2523Human Brain MappingJoint attention behaviors include initiating one's own and responding to another's bid for joint attention to an object, person, or topic. Joint attention abilities in autism are pervasively atypical, correlate with development of language and social abilities, and discriminate children with autism from other developmental disorders. Despite the importance of these behaviors, the neural correlates of joint attention in individuals with autism remain unclear. This paucity of data is likely due to the inherent challenge of acquiring data during a real-time social interaction. We used a novel experimental set-up in which participants engaged with an experimenter in an interactive face-to-face joint attention game during fMRI data acquisition. Both initiating and responding to joint attention behaviors were examined as well as a solo attention (SA) control condition. Participants included adults with autism spectrum disorder (ASD) (n = 13), a mean age- and sex-matched neurotypical group (n = 14), and a separate group of neurotypical adults (n = 22). Significant differences were found between groups within social-cognitive brain regions, including dorsal medial prefrontal cortex (dMPFC) and right posterior superior temporal sulcus (pSTS), during the RJA as compared to SA conditions. Region-of-interest analyses revealed a lack of signal differentiation between joint attention and control conditions within left pSTS and dMPFC in individuals with ASD. Within the pSTS, this lack of differentiation was characterized by reduced activation during joint attention and relative hyper-activation during SA. These findings suggest a possible failure of developmental neural specialization within the STS and dMPFC to joint attention in ASD.nonotspecifiedhttp://www.cyberneum.de/published-2511Atypical brain activation patterns during a face-to-face joint attention game in adults with autism spectrum disorder1501715422EngelC20133DEngelCCurio2013-10-0045146157IEEE Intelligent Transportation Systems MagazineA driver assistance system realizes that the driver is distracted and that a potentially hazardous situation is emerging. In this scenario the driver needs to make an optimal decision as fast as possible. His attention needs to be directed to the location that enhances the perception of all action relevant entities. But where is that optimal spot? Pedestrian detectability is a measure of the probability that a driver perceives pedestrians in static and dynamic scenes. Leveraging this information allows a driver assistance system to direct the attention of the driver to the spot that maximizes the probability that all pedestrians are seen.nonotspecifiedhttp://www.cyberneum.de/published11Detectability Prediction for Increased Scene Awareness1501715422BarnettCowanB20133MBarnett-CowanHHBülthoff2013-10-00536544545Behavioral and Brain SciencesJeffery et al. propose a non-uniform representation of three-dimensional space during navigation. Fittingly, we recently revealed asymmetries between horizontal and vertical path integration in humans. We agree that representing navigation in more than two dimensions increases computational load and suggest that tendencies to maintain upright head posture may help constrain computational processing, while distorting neural representation of three-dimensional navigation.nonotspecifiedhttp://www.cyberneum.de/published1Human path navigation in a three-dimensional world1501715422MeilingerFB20133TMeilingerJFrankensteinHHBülthoff2013-10-00112924–30CognitionPeople use “route knowledge” to navigate to targets along familiar routes and “survey knowledge” to determine (by pointing, for example) a target’s metric location. We show that both root in separate memories of the same environment: participants navigating through their home city relied on representations and reference frames different from those they used when doing a matched survey task. Tübingen residents recalled their way along a familiar route to a distant target while located in a photorealistic virtual 3D model of Tübingen, indicating their route decisions on a keyboard. Participants had previously done a survey task (pointing) using the same start points and targets. Errors and response latencies observed in route recall were completely unrelated to errors and latencies in pointing. This suggests participants employed different and independent representations for each task. Further, participants made fewer routing errors when asked to respond from a horizontal walking perspective rather than a constant aerial perspective. This suggests that instead of the single reference, north-up frame (similar to a conventional map) they used in the survey task, participants employed different, and most probably multiple, reference frames learned from “on the ground” navigating experience. The implication is that, within their everyday environment, people use map or navigation-based knowledge according to which best suits the task.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/Cognition-2013-Meilinger.pdfpublished-24Learning to navigate: Experience versus maps1501715422vonLassbergRMK20133Cvon LassbergWRappBMohlerJKrug2013-10-005231124–1130Journal of Electromyography and KinesiologyIn several athletic disciplines there is evidence that for generating the most effective acceleration of a specific body part the transfer of momentum should run in a “whip-like” consecutive succession of body parts towards the segment which shall be accelerated most effectively (e.g. the arm in throwing disciplines). This study investigated the question how this relates to the succession of neuromuscular activation to induce such “whip like” leg acceleration in sports like gymnastics with changed conditions concerning the body position and momentary rotational axis of movements (e.g. performing giant swings on high bar). The study demonstrates that during different long hang elements, performed by 12 high level gymnasts, the succession of the neuromuscular activation runs primarily from the bar (punctum fixum) towards the legs (punctum mobile). This demonstrates that the frequently used teaching instruction, first to accelerate the legs for a successful realization of such movements, according to a high level kinematic output, is contradictory to the neuromuscular input patterns, being used in high level athletes, realizing these skills with high efficiency.
Based on these findings new approaches could be developed for more direct and more adequate teaching methods regarding to an earlier optimization and facilitation of fundamental movement requirements.nonotspecifiedhttp://www.cyberneum.de/published-1124Neuromuscular onset succession of high level gymnasts during dynamic leg acceleration phases on high bar1501715422BiegBBC20133H-JBiegJ-PBrescianiHHBülthoffLLChuang2013-10-003230271281Experimental Brain ResearchWe investigate how smooth pursuit eye movements affect the latencies of task-switching saccades. Participants had to alternate their foveal vision between a continuous pursuit task in the display center and a discrete object discrimination task in the periphery. The pursuit task was either carried out by following the target with the eyes only (ocular) or by steering an on-screen cursor with a joystick (oculomanual). We measured participants’ saccadic reaction times (SRTs) when foveal vision was shifted from the pursuit task to the discrimination task and back to the pursuit task. Our results show asymmetries in SRTs depending on the movement direction of the pursuit target: SRTs were generally shorter in the direction of pursuit. Specifically, SRTs from the pursuit target were shorter when the discrimination object appeared in the motion direction. SRTs to pursuit were shorter when the pursuit target moved away from the current fixation location. This result was independent of the type of smooth pursuit behavior that was performed by participants (ocular/oculomanual). The effects are discussed in regard to asymmetries in attention and processes that suppress saccades at the onset of pursuit.nonotspecifiedhttp://www.cyberneum.de/published10Saccade reaction time asymmetries during task-switching in pursuit tracking1501715422ZhaoB2013_23MZhaoIBülthoff2013-10-00621722725Visual Cognitionnonotspecifiedhttp://www.cyberneum.de/published3The other-race effect in face recognition is sensitive to face format at encoding1501715422delaRosaMBC20133Sde la RosaSMieskesHHBülthoffCCurio2013-10-007524110Frontiers in PsychologyRecognizing social interactions, e.g. two people shaking hands, is important for obtaining information about other people and the surrounding social environment. Despite the visual complexity of social interactions, humans have often little difficulties to visually recognize social interactions. What is the visual representation of social interactions and the bodily visual cues that promote this remarkable human ability? Viewpoint dependent representations are considered to be at the heart of the visual recognition of many visual stimuli including objects (Bülthoff & Edelman, 1992), and biological motion patterns (Verfaillie, 1993). Here we addressed the question whether complex social actions acted out between pairs of people, e.g. hugging, are also represented in a similar manner. To this end, we created 3-D models from motion captured actions acted out by two people, e.g. hugging. These 3-D models allowed to present the same action from different viewpoints. Participants task was to discriminate a target action from distractor actions using a one-interval-forced-choice (1IFC) task. We measured participants' recognition performance in terms of reaction times (RT) and d-prime (d'). For each tested action we found one view that lead to superior recognition performance compared to other views. This finding demonstrates view-dependent effects of visual recognition, which are in line with the idea of a view dependent representations of social interactions. Subsequently, we examined the degree to which velocities of joints are able to predict the recognition performance of social interactions in order to determine candidate visual cues underlying the recognition of social interactions. We found that the velocities of the right arm, lower left leg, and both feet correlated with recognition performance.nonotspecifiedhttp://www.cyberneum.de/published9View dependencies in the visual recognition of social interactions1501715422KimCCPBK20137JKimYGChungS-CChungJ-YParkHHBülthoffS-PKimGwangju, South Korea2013-10-001637164013th International Conference on Control, Automation and Systems (ICCAS 2013)Previous neural decoding studies have mainly focused on discrimination of activation patterns evoked by active movements. Nonetheless, comparatively, little attention has been devoted toward understanding how brain signals are observed with passive stimulus. In this study, we examined whether the stimulus locations on between fingers, one of the most fundamental features of passive vibrotactile stimulation, can be distinguished from human functional magnetic resonance imaging (fMRI) data. Whole brain searchlight multi-voxel pattern analysis (MVPA) has found two brain regions, which make a contribution to decode stimulus sites, in contralateral posterior parietal cortex (PPC) and contralateral secondary somatosensory cortex (S2). No significant area for the decoding of activity to stimulus site in primary somatosensory cortex (S1), which is well-developed brain region for finger somatotopy. On the other hand, a whole brain univariate group analysis has discovered activity in S1, not in PPC and S2 areas. These results suggest that PPC and S2 regions play a key role in the differentiation of passive vibrotactile stimulus locations, and thus decode tactile events from finger somatotopic.nonotspecifiedhttp://www.cyberneum.de/published3A multi-voxel pattern analysis of neural representation of vibrotactile location1501715422KrupchankaK2013_27DKrupchankaMKatliarBarcelona, Spain2013-10-00S44026th European College of Neuropsychopharmacology Congress (ECNP 2013)nonotspecifiedhttp://www.cyberneum.de/published0Insight mediates link between stigma and depression in schizophrenia1501715422Bulthoff2013_710HHBülthoffRyllBR2013_27MRyllHHBülthoffPRobuffo GiordanoRoma, Italy2013-09-256th International Workshop on Human-Friendly Robotics (HFR 2013)In this work we present a novel concept of a quadrotor UAV with tilting propellers. Standard quadrotors are limited in their mobility and ability to interact with the environment because of their intrinsic underactuation (only 4 independent control inputs vs. their 6-dof pose in space). The proposed quadrotor prototype, on the other hand, has the ability to also control the orientation of its 4 propellers, thus making it possible to overcome the aforementioned underactuation and behave as a fully-actuated flying vehicle. We first describe the control design of our actuated UAV, illustrate the hardware and
software specification of our flying prototype, and finally show a future perspective for an interaction task between the UAV and the environment.nonotspecifiedhttp://www.cyberneum.de/published0Overactuation in UAVs for Enhanced Aerial Manipulation: A Novel Quadrotor Concept with Tilting1501715422NestmeyerRF2013_210TNestmeyerPRobuffo GiordanoAFranchiChang2013_210D-SChangChang2013_310D-SChangQuarantaMV20133GQuarantaPMasaratiJVenrooij2013-09-00203324948–4962Journal of Sound and VibrationThe coupling of rotorcraft dynamics with the dynamics of one of the main systems devoted to its control, the pilot, may lead to several peculiar phenomena, known as Rotorcraft–Pilot Couplings (RPCs), all characterized by an abnormal behavior that may jeopardize flight safety. Among these phenomena, there is a special class of couplings which is dominated by the biodynamic behavior of the pilot's limbs that close the loop between the vibrations and the control inceptors in the cockpit. Leveraging robust stability analysis, the inherently uncertain pilot biodynamics can be treated as the uncertain portion of a feedback system, making analytical, numerical or graphical determination of proneness to RPC possible by comparing robust stability margins of helicopter models with experimental Biodynamic Feedthrough (BDFT) data. The application of the proposed approach to collective bounce is exemplified using simple analytical helicopter and pilot models. The approach is also applied to detailed helicopter models and experimental BDFT measurement data.nonotspecifiedhttp://www.cyberneum.de/published-4948Impact of pilots’ biodynamic feedthrough on rotorcraft by robust stability1501715422FranchiOS20133AFranchiGOrioloPStegagno2013-09-00113213021322International Journal of Robotics ResearchWe propose a decentralized method to perform mutual localization in multi-robot systems using anonymous relative measurements, i.e. measurements that do not include the identity of the measured robot. This is a challenging and practically relevant operating scenario that has received little attention in the literature. Our mutual localization algorithm includes two main components: a probabilistic multiple registration stage, which provides all data associations that are consistent with the relative robot measurements and the current belief, and a dynamic filtering stage, which incorporates odometric data into the estimation process. The design of the proposed method proceeds from a detailed formal analysis of the implications of anonymity on the mutual localization problem. Experimental results on a team of differential-drive robots illustrate the effectiveness of the approach, and in particular its robustness against false positives and negatives that may affect the robot measurement process. We also provide an experimental comparison that shows how the proposed method outperforms more classical approaches that may be designed building on existing techniques. The source code of the proposed method is available within the MLAM ROS stack.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/2013g-FraOriSte.pdfpublished20Mutual Localization in Multi-Robot Systems using Anonymous Relative Measurements1501715422MeilingerB20133TMeilingerHHBülthoff2013-09-009819PLoS ONESpatial memory is thought to be organized along experienced views and allocentric reference axes. Memory access from different perspectives typically yields V-patterns for egocentric encoding (monotonic decline in performance along with the angular deviation from the experienced perspectives) and W-patterns for axes encoding (better performance along parallel and orthogonal perspectives than along oblique perspectives). We showed that learning an object array with a verbal secondary task reduced W-patterns compared with learning without verbal shadowing. This suggests that axes encoding happened in a verbal format; for example, by rows and columns. Alternatively, general cognitive load from the secondary task prevented memorizing relative to a spatial axis. Independent of encoding, pointing with a surrounding room visible yielded stronger W-patterns compared with pointing with no room visible. This suggests that the visible room geometry interfered with the memorized room geometry. With verbal shadowing and without visual interference only V-patterns remained; otherwise, V- and W-patterns were combined. Verbal encoding and visual interference explain when W-patterns can be expected alongside V-patterns and thus can help in resolving different performance patterns in a wide range of experiments.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/PLoS-ONE-2013-Meilinger.pdfpublished8Verbal Shadowing and Visual Interference in Spatial Memory1501715422BreidtBC20137MBreidtHHBülthoffCCurioBath, UK2013-09-00414811th Conference on Theory and Practice of Computer Graphics (TP.CG.2013)Parameterized, high-fidelity 3D surface models can not only be used for rendering animations in the context of Computer Graphics (CG), but have become increasingly popular for analyzing data, and thus making these accessible to CG systems in an Analysis-by-Synthesis loop. In this paper, we utilize this concept for accurate head tracking by fitting a statistical 3D model to marker-less face data acquired with a low-cost depth sensor, and demonstrate its robustness in a challenging car driving scenario. We compute 3D head position and orientation with a mesh-based 3D shape matching algorithm that is independent of person identity and sensor type, and at the same time robust to facial expressions, speech, partial occlusion and illumination changes. Different strategies for obtaining the 3D face model are evaluated, trading off computational complexity and accuracy. Ground truth data for head pose are obtained from simultaneous marker-based tracking. Average tracking errors are below 6mm for head position and below 2.5 for head orientation, demonstrating the system's potential to be used as part of a non-intrusive head tracking system for use in Augmented Reality or driver assistance systems.nonotspecifiedhttp://www.cyberneum.de/published7Accurate and marker-less head tracking using depth sensors1501715422GrabeRBRF20137VGrabeMRiedelHHBülthoffPRobuffo GiordanoAFranchiBarcelona, Spain2013-09-0019256th European Conference on Mobile Robots (ECMR 2013)The free and open source Tele-Operation Platform of the MPI for Biological Cybernetics (TeleKyb) is an end- to-end software framework for the development of bilateral teleoperation systems between human interfaces (e.g., haptic force feedback devices or gamepads) and groups of quadrotor Unmanned Aerial Vehicles (UAVs). Among drivers for devices and robots from various hardware manufactures, TeleKyb provides a high-level closed-loop robotic controller for mobile robots that can be extended dynamically with modules for state estimation, trajectory planning, processing, and tracking. Since all internal communication is based on the Robot Operating System (ROS), TeleKyb can be easily extended to meet future needs. The capabilities of the overall framework are demonstrated in both an experimental validation of the controller for an individual quadrotor and a complex experimental setup involving bilateral human-robot interaction and shared formation control of multiple UAVs.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/2013j-GraRieBueRobFra-preprint.pdfpublished6The TeleKyb Framework for a Modular and Extendible ROS-based Quadrotor Control1501715422VosgerauKMV20132GVosgerauAKnollTMeilingerKVogeleyMetzlerStuttgart, Germany2013-09-00386401Handbuch Kognitionswissenschaftnonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/vosgerau_et_al_2013_repraesentation_proof.pdfpublished15Repräsentation1501715422RoheN20137TRoheUNoppeneyTübingen, Germany2013-09-00170Bernstein Conference 2013To form coherent and reliable multisensory percepts of the environment, human observers have to segregate multisensory signals caused by independent sources but integrate those from a common source. Models of causal inferences (Kording et al., 2007) predict the inference of a common cause if the signals are close in space and time. Further, models of optimal reliability-weighted integration predict that multisensory signals are weighed proportional to their relative reliability in order to maximize the reliability of the integrated percept (Ernst & Banks, 2002). To probe models of causal inference and reliability-weighted integration, we presented subjects (N = 26) with audiovisual spatial cues and manipulated spatial disparity and visual reliability. Subjects were required to selectively localize the auditory cues and to judge the spatial unity of the cues. Indices of audiovisual spatial integration showed that audiovisual spatial cues were weighted proportional to visual reliability, but only if a common cause was inferred. Likewise, localization reliability increased with visual reliability in case of a common-cause inference. Computational models incorporating causal inferences and reliability-weighted integration provided superior fit to auditory-localization data compared to models implementing only reliability-weighted integration. The results suggest that reliability-weighed integration is conditioned on the outcome of the causal inference.nonotspecifiedhttp://www.cyberneum.de/published-170Causal inference conditions reliability-weighted integration of audiovisual spatial signals1501715422PariseKE2013_27CVPariseKKnorreMErnstTübingen, Germany2013-09-0077Bernstein Conference 2013The association between sound frequency and spatial elevation is a remarkable example of cross-dimensional sensory mapping. In a wide range of cognitive, perceptual, attentional, and linguistic functions, humans consistently display a positive, sometimes absolute, association between sound frequency and spatial elevation, whereby increasing frequency is mapped to increasing elevation. However, a comprehensive account for the origins of such a pervasive cross-dimensional link is still missing. Here we demonstrate that the frequency-elevation mapping observed in human behaviour is already present in both the statistics of the acoustic stimuli in the environment, and in the filtering properties of the external ear. Specifically, we singled out the effects of head- and world-centred elevation and, through a combined analysis of environmental sounds and anthropometric measures, we show that, (1) in world-centred coordinates, high sounds are statistically more likely to come from higher elevations; moreover, (2) due to the external ear, sounds coming from higher head-centred elevations have more energy at high frequencies. To link these findings to human cognition, in a psychophysical task observers localized narrow band noises with different central frequencies, while head- and world-centred elevations were put into conflict by tilting participants’ body. Sound frequency systematically biased localization in both head- and world-centred coordinates in agreement with the mappings measured in the ear and the environment. We argue that, in a shorter timescale, humans learn the statistics of the auditory signals; while, in a longer timescale, evolution might tune the filtering properties of the external ear to the statistics of the acoustic environment.nonotspecifiedhttp://www.cyberneum.de/published-77On pitch-elevation mapping: Nature, nurture and behaviour15017154221501718824GauN20137RGauUNoppeneyTübingen, Germany2013-09-00169Bernstein Conference 2013In the natural environment our senses are bombarded with many different signals. To form a coherent percept, the brain should integrate signals originating from a common source and segregate signals from different sources. This fMRI study investigated how humans combine bottom-up inputs (i.e. congruent VS incongruent signals) and top-down predictions (i.e. common source prior) to infer if sensory signals should be integrated. Sixteen participants were shown movies of congruent (e.g. visual Ti with auditory Ti), incongruent (e.g. visual Ti with auditory Pi) and McGurk syllables (e.g. visual Ki with auditory Pi, which can be fused into the illusionary percept Ti). We manipulated participants’ top-down predictions by presenting the McGurk stimuli in a series of congruent or incongruent syllables. Participants reported their syllable percept in forced choice procedure with 6 response options. At the behavioural level, participants were more likely to fuse auditory and visual signals of a McGurk trial into an illusionary percept in congruent relative to incongruent contexts. This indicates that participant’s top-down predictions influence whether or not they integrate sensory signals. At the neural level, incongruent relative to congruent bottom-up inputs increased activations in a left fronto-parietal network. The left prefrontal activations also increased for McGurk trials, when participants selectively reported their auditory percept and did not fuse auditory and visual signals. This effect was enhanced for incongruent contexts when participants expected that sensory signals needed to be segregated. Our results show that the left inferior frontal sulcus determines whether sensory signals should be integrated by combining top-down predictions generated from prior trials with bottom-up information about sensory conflict in the incoming signals. Furthermore, it exerts top-down control enabling independent sensory processing and report of only one sensory modality.nonotspecifiedhttp://www.cyberneum.de/published-169The left prefrontal cortex controls information integration by combining bottom-up inputs and top-down predictions1501715422CurioCG201310CCurioEChiovettoMAGiesePariseE2013_210CVPariseMErnstHerdtweck201315CHerdtweck2013-08-26nonotspecifiedpublishedLearning Data-Driven Representations for Robust Monocular Computer Vision Applications1501715422Kleiner201310MKleinerConradKBHBN20133VConradMKleinerABartelsJHartcher O'BrienHHBülthoffUNoppeney2013-08-008818PLoS ONERapid integration of biologically relevant information is crucial for the survival of an organism. Most prominently, humans should be biased to attend and respond to looming stimuli that signal approaching danger (e.g. predator) and hence require rapid action. This psychophysics study used binocular rivalry to investigate the perceptual advantage of looming (relative to receding) visual signals (i.e. looming bias) and how this bias can be influenced by concurrent auditory looming/receding stimuli and the statistical structure of the auditory and visual signals.
Subjects were dichoptically presented with looming/receding visual stimuli that were paired with looming or receding sounds. The visual signals conformed to two different statistical structures: (1) a ‘simple’ random-dot kinematogram showing a starfield and (2) a “naturalistic” visual Shepard stimulus. Likewise, the looming/receding sound was (1) a simple amplitude- and frequency-modulated (AM-FM) tone or (2) a complex Shepard tone. Our results show that the perceptual looming bias (i.e. the increase in dominance times for looming versus receding percepts) is amplified by looming sounds, yet reduced and even converted into a receding bias by receding sounds. Moreover, the influence of looming/receding sounds on the visual looming bias depends on the statistical structure of both the visual and auditory signals. It is enhanced when audiovisual signals are Shepard stimuli.
In conclusion, visual perception prioritizes processing of biologically significant looming stimuli especially when paired with looming auditory signals. Critically, these audiovisual interactions are amplified for statistically complex signals that are more naturalistic and known to engage neural processing at multiple levels of the cortical hierarchy.nonotspecifiedhttp://www.cyberneum.de/published7Naturalistic Stimulus Structure Determines the Integration of Audiovisual Looming Signals in Binocular Rivalry15017154221501718826TakahashiMWB20133KTakahashiTMeilingerKWatanabeHHBülthoff2013-08-00580717Frontiers in Human NeuroscienceResearches on embodied perception have revealed that social, psychological and physiological factors influence perception of space. While many of these influences were observed with real or highly realistic stimuli, the present work showed that even the orientation of abstract geometric objects with a non-realistic virtual environment could influence distance perception. Observers wore a head mounted display and watched virtual cones moving within an invisible cube for five seconds with their head movement recorded. Subsequently, observers estimated the distance to the cones or evaluated their friendliness. The cones either faced the observer, a target behind the cones, or random orientations. Average viewing distance to the cones varied between 1.2 and 2.0 m. At a viewing distance of 1.6 m, observers perceived cones facing them as closer than cones facing an opposite target or random orientations. Furthermore, irrespective of viewing distance, observers moved their head away from the cones more strongly and evaluated the cones as less friendly when the cones were facing observers. Similar results of distance estimation were obtained with a 3D projection onto a large screen, although the effective viewing distance was farther away. These results suggest that factors other than physical distance could influence distance perception even with non-realistic geometric objects within a virtual environment. Furthermore, the modulation of distance perception was also accompanied by changes in subjective impression and avoidance movement. We propose that cones facing an observer are perceived as socially discomforting or threatening and potentially violate an observer’s personal space, which might influence the perceived distance of cones.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/FHN-2013-Takahashi.pdfpublished6Psychological influences on distance estimation in a virtual reality environment1501715422LeeFSHBR20133DLeeAFranchiHISonCSHaHHBülthoffPRobuffo Giordano2013-08-0041813341345IEEE/ASME Transactions on MechatronicsWe propose a novel semiautonomous haptic teleoperation control architecture for multiple unmanned aerial vehicles (UAVs), consisting of three control layers: 1) UAV control layer, where each UAV is abstracted by, and is controlled to follow the trajectory of, its own kinematic Cartesian virtual point (VP); 2) VP control layer, which modulates each VP’s motion according to the teleoperation commands and local artificial potentials (for VP–VP/VP-obstacle collision avoidance and VP–VP connectivity preservation); and 3) teleoperation layer, through which a single remote human user can command all (or some) of the VPs’ velocity while haptically perceiving the state of all (or some) of the UAVs and obstacles. Master passivity/slave stability and some asymptotic performance measures are proved. Experimental results using four custom-built quadrotor-type UAVs are also presented to illustrate the theory.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/2013b-LeeFraSonBueRob_01.pdfpublished11Semiautonomous Haptic Teleoperation Control Architecture of Multiple Unmanned Aerial Vehicles1501715422delaRosaSGBC20177Sde la RosaSStreuberMGieseHHBülthoffCCurioBerlin, Germany2013-08-00391535th Annual Conference of the Cognitive Science Society (CogSci 2013)Action recognition is important for social interactions. Because little is known about the visual tuning properties
of processes involved in action recognition, we examined the visual tuning properties of action recognition by means of a behavioral adaptation paradigm. Participants were adapted to images showing a person hitting or waving and subsequently categorized test images showing an ambiguous action as either hitting or waving. We found the perception of the test images to be significantly biased away from the adapted action (action adaptation aftereffect (AAA)). Subsequent experiments ruled out that the AAA was not merely driven by the adaptation of local visual contrast or the emotional content of the action. However adaptation to action words (e.g. “hitting” or “waving”) did not induce an AAA. Finally we found evidence for the AAA being
modulated by the social context in which an action is embedded, suggesting high level influences on action recognition.nonotspecifiedhttp://www.cyberneum.de/published-3915High level influences on visual action recognition1501715422delaRosaCBC20137Sde la RosaRChoudheryHBülthoffCCurioBremen, Germany2013-08-0019336th European Conference on Visual Perception (ECVP 2013)There is ample evidence for gender specific mating preferences: While women tend to put more importance on men's reproductive capabilities, men tend to favor female attractiveness when selecting a partner. Here we explored whether looking at attractive people induces emotions in the observer. We presented images of faces to participants (40 male and 40 females) and subsequently asked participants about their current emotional state. Specifically, we manipulated the gender (male vs. female) and the attractiveness (normal vs. attractive) of the presented faces and asked participants to report their felt happiness, sadness, and attractedness. We found that both men and women felt more attracted to attractive faces, as opposed to average faces of the opposite gender (p<0.05), but only men felt happier looking at attractive women and felt more sad looking at normal looking women (p<0.001). This result suggests a gender specific effect of attractiveness on happiness that is in line with existing theories about human mating preferences.nonotspecifiedhttp://www.cyberneum.de/published-193Eye candy: Looking at attractive people of the opposite gender makes men happy but not woman1501715422KaulardSBd20137KKaulardJWSchultzHBülthoffSde la RosaBremen, Germany2013-08-0019236th European Conference on Visual Perception (ECVP 2013)What do you have in mind when judging the similarity of two facial expressions? This study investigates how facial expression attributes are linked to the perceived similarity of facial expressions. Participants were shown pictures and videos of 2 types of facial expressions: 6 emotional (e.g. happy) and 6 conversational (e.g. don’t understand) expressions. One group of participants was asked to rate several attributes of those expressions (e.g. “how much is the person in control of the situation”, “how much does the mouth move”). Another group rated the pairwise similarity of the expressions. We explored the link between attribute ratings and perceived similarity of expressions using multiple regression analysis. The analysis revealed that different attributes best predicted the similarity ratings of pictures and videos of both facial expressions types, suggesting different evaluation strategies. To rule out the possibility that representational spaces based on expression attributes are different across pictures and videos of both expression types, principal component analysis (PCA) was applied. Significant correlations between all PCA results suggest that those representations are similar. In sum, our study suggests different evaluative strategies for pairwise similarity judgments of pictures and videos of emotional and conversational expressions, despite similar representational spaces for these stimuli.nonotspecifiedhttp://www.cyberneum.de/published-192How we evaluate what we see - the interplay between the perceptual and conceptual structure of facial expressions1501715422SaultondB20137ASaultonSde la RosaHBülthoffBremen, Germany2013-08-0017636th European Conference on Visual Perception (ECVP 2013)Recent studies have investigated the body representation underlying tactile size perception and position sense. These studies have shown distorted hand representations consisting of an overestimation of hand width and an underestimation of finger length [Longo and Haggard, 2010, PNAS, 107(26), 11727- 11732]. Here, we are interested in whether the observed distortions are specific to the hand or can be also detected with objects (star, box, rake, circle). Participants judged the location in external space of predefined landmarks on the hand and objects. We compared the actual and estimated horizontal and vertical distances between landmarks. Our results replicate previously reported significant underestimations of the finger length (vertical axis). There was no significant overestimation of the hand width. In the case of objects, we found a significant underestimation along the vertical axis for all objects (p<0.01), which was smaller than for the hand (p<0.05). There was no significant distortion along the horizontal axis for the star. We observed significant horizontal underestimations for the circle and the box, and a significant overestimation for the rake (p<0.05). In summary, distortions along the vertical axis also occur for objects. However, the size of the vertical distortion was larger for the hand than for the objects.nonotspecifiedhttp://www.cyberneum.de/published-176Implicit spatial representation of objects and hand size1501715422ZhaoB20137MZhaoIBülthoffBremen, Germany2013-08-0020436th European Conference on Visual Perception (ECVP 2013)People recognize own-race faces more accurate than those of other races. This other-race effect (ORE) has been frequently observed when faces are learned from static, single view images. However, the single-view face learning may prevent the acquisition of useful information (e.g., 3D face shape) for recognizing unfamiliar, other-race faces. Here we tested whether learning faces from multiple viewpoints reduces the ORE. In Experiment 1 participants learned faces from a single viewpoint (left or right 15° view) and were tested with front view(0° view) using an old/new recognition task. They showed better recognition performances for own-race faces than that for other-race faces, demonstrating the ORE in face recognition across viewpoints. In Experiment 2 participants learned each face from four viewpoints (in order, left 45°, left 15°, right 15°, and right 45° views) and were tested in the same way as in Experiment 1. Participants recognized own- and other-race faces equally well, eliminating the ORE. These results suggest that learning faces from multiple viewpoints improves the recognition of other-race faces more than that for own-race faces, and that previously observed ORE is caused in part by the non-optimal encoding condition for other-race faces.nonotspecifiedhttp://www.cyberneum.de/published-204Learning Faces from Multiple Viewpoints Eliminates the Other-Race Effect1501715422BrielmannBA20137ABrielmannIBülthoffRArmannBremen, Germany2013-08-0020436th European Conference on Visual Perception (ECVP 2013)The other-race effect is the widely known difficulty at recognizing faces of another race. Further, it has been clearly established in eye tracking studies that observers of different cultural background exhibit different viewing strategies. Whether those viewing strategies depend also on the type of faces shown (same-race vs. other-race faces) is under much debate. Using eye tracking, we investigated whether European observers look at different facial features when viewing Asian and Caucasian faces in a face race categorization task. Additionally, to investigate the influence of viewpoints on gaze patterns, we presented faces in frontal, half profile and profile views. Even though fixation patterns generally changed across views, fixations to the eyes were more frequent for Caucasian faces and fixations to the nose were more frequent for Asian faces, independent of face orientation. In contrast, how fixations to cheeks, mouth and outline regions changed according to the face’s race was also dependent on face orientations. In sum, our results indicate that we mainly look at prominent facial features, albeit which features are fixated most often critically depends on face race and orientation.nonotspecifiedhttp://www.cyberneum.de/published-204Looking at faces from different angles: Europeans fixate different features in Asian and Caucasian faces1501715422ChangBd20137D-SChangHHBülthoffSde la RosaDublin, Ireland2013-08-00128ACM Symposium on Applied Perception (SAP '13)We wanted to investigate whether judgments of personality traits based on brief visual observations, namely the 'thin slicing' approach, can also be replicated with biological motion cues consisting of point-light stimuli when different sorts of natural human actions were carried out. We captured six different actions carried out by ten different people using a motion capture system. These actions were then judged in terms of various personal traits by 18 different raters. All actors who recorded those actions were also included as raters. The results showed significant consistency in both the ratings across different raters (inter-rater-reliability) and the ratings between the items (inter-item-reliability). Moreover, accuracy of judgments was also found with self-ratings showing a significant correlation with other people's ratings for a number of different trait judgments.nonotspecifiedhttp://www.cyberneum.de/published-128Making Trait Judgments based on Biological Motion Cues: A Thinslicing Approach1501715422VolkovaMDTB20137EKVolkovaBJMohlerTDoddsJTeschHHBülthoffDublin, Ireland2013-08-00135ACM Symposium on Applied Perception (SAP '13)People use body motion to express and recognise emotions. We investigated whether emotional body expressions can be recognised when they are recorded during natural narration, where actors freely express the emotional colouring of a story told. We then took only the upper body motion trajectories and presented them to participants in the form of animated stick figures. The observers were asked to categorise the emotions expressed in short motion sequences. The results show that recognition level of eleven emotions shown via upper body is significantly above chance level and the responses to motion sequences are consistent across observers.nonotspecifiedhttp://www.cyberneum.de/published-135Perception of emotional body expressions in narrative scenarios1501715422DobsBBVCS20137KDobsIBülthoffMBreidtQCVuongCCurioJWSchultzBremen. Germany2013-08-0019736th European Conference on Visual Perception (ECVP 2013)A great deal of social information is conveyed by facial motion. However, understanding how observers use the natural timing and intensity information conveyed by facial motion is difficult because of the complexity of these motion cues. Here, we systematically manipulated animations of facial expressions to investigate observers’ sensitivity to changes in facial motion. We filmed and motion-captured four facial expressions and decomposed each expression into time courses of semantically meaningful local facial actions (e.g., eyebrow raise). These time courses were used to animate a 3D head model with either the original time courses or approximations of them. We then tested observers’ perceptual sensitivity to these changes using matching-to-sample tasks. When viewing two animations (original vs. approximation), observers chose original animations as most similar to the video of the expression. In a second experiment, we used several measures of stimulus similarity to explain observers’ choice of which approximation was most similar to the original animation when viewing two different approximations. We found that high-level cues about spatio-temporal characteristics of facial motion (e.g., onset and peak of eyebrow raise) best explained observers’ choices. Our results demonstrate the usefulness of our method; and importantly, they reveal observers’ sensitivity to natural facial dynamics.nonotspecifiedhttp://www.cyberneum.de/published-197Quantifying Human Sensitivity to Spatio-Temporal Information in Dynamic Faces1501715422WellerdiekLVCM20137ACWellerdiekMLeyrerEVolkovaD-SChangBMohlerDublin, Ireland2013-08-00138ACM Symposium on Applied Perception (SAP '13)Most of the time point-light figures are used for motion-recognition, which present motions by only displaying the moving joints of the actor. In this study we were interested in whether self-recognition of motion changes with different representations. First, we captured participants' motions and remapped them on a point-light figure and a male and female virtual avatar. In the second part the same participants were asked to recognize their own motions on all three representations. We found that the recognition rate for own motions is high across all representations and different actions. The recognition rate was better on the point-light figure, despite being perceived as most difficult from the participants. The gender of the visual avatar did not matter in self-recognition.nonotspecifiedhttp://www.cyberneum.de/published-138Recognizing your own motions on virtual avatars: is it me or not?1501715422SchultzBK20137JWSchultzHBülthoffKKaulardBremen, Germany2013-08-005536th European Conference on Visual Perception (ECVP 2013)Processing social information contained in facial motion is likely to involve neural mechanisms in hierarchically organized brain regions. To investigate processing of facial expressions, we acquired functional magnetic imaging data from 11 participants observing videos of 12 facial expressions. Stimuli were presented upright (clearly perceivable social information) and upside-down (disrupted social information). We assessed the amount of information contained in the brain activation patterns evoked by these expressions with multivariate searchlight analyses. We found reliable above-chance decoding performance for upright stimuli only in the left superior temporal sulcus region (STS) and for inverted stimuli only in the early visual cortex (group effects, corrected for family-wise errors resulting from multiple comparisons across gray matter voxels). Predictive coding proposes that inferences from high-level areas are subtracted from incoming sensory information in lower-level areas through feedback. Accordingly, we propose that upright stimuli activate representations of facial expressions in STS, which induces feedback to early visual areas and reduced processing in those regions. In contrast, we propose that upside-down stimuli fail to activate representations in STS and thus are processed longer in early visual cortex. Predictive coding might prove a useful framework for studying the network of brain regions processing social information.nonotspecifiedhttp://www.cyberneum.de/published-55Signs of predictive coding in dynamic facial expression processing1501715422SaultonDTMB20137ASaultonTJDoddsJTeschBJMohlerHHBülthoffDublin, Ireland2013-08-00142ACM Symposium on Applied Perception (SAP '13)The ability of humans to apprehend the overall size or volume of an indoor space is not well understood. Previous research has highlighted a 'rectangularity illusion', in which rectangular rooms appear to be larger than square rooms of the same size (identical volume), showing that the subjective perceived space cannot be explained from the mathematical formula for volume, i.e. length × width × height. Instead, the results suggest that one might use the longest dimension of the space as a simplified strategy to assess room size [Sadalla and Oxley 1984].nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/SAP-2013-Saulton.pdfpublished-142The influence of shape and culture on visual volume perception of virtual rooms1501715422Dobricki2013_410MDobrickiBulthoff201310HHBülthoffErdenizRDS20133BErdenizTRoheJDoneRDSeidler2013-07-00116716Frontiers in NeuroscienceConventional neuroimaging techniques provide information about condition-related changes of the BOLD (blood-oxygen-level dependent) signal, indicating only where and when the underlying cognitive processes occur. Recently, with the help of a new approach called “model-based” functional neuroimaging (fMRI), researchers are able to visualize changes in the internal variables of a time varying learning process, such as the reward prediction error or the predicted reward value of a conditional stimulus. However, despite being extremely beneficial to the imaging community in understanding the neural correlates of decision variables, a model-based approach to brain imaging data is also methodologically challenging due to the multicollinearity problem in statistical analysis. There are multiple sources of multicollinearity in functional neuroimaging including investigations of closely related variables and/or experimental designs that do not account for this. The source of multicollinearity discussed in this paper occurs due to correlation between different subjective variables that are calculated very close in time. Here, we review methodological approaches to analyzing such data by discussing the special case of separating the reward prediction error signal from reward outcomes.nonotspecifiedhttp://www.cyberneum.de/published5A simple solution for model comparison in bold imaging: the special case of reward prediction error and reward outcomes1501715422SoykaBB20133FSoykaHHBülthoffMBarnett-Cowan2013-07-0012285162Experimental Brain ResearchIn this paper, we show that differences in reaction times (RT) to self-motion depend not only on the duration of the profile, but also on the actual time course of the acceleration. We previously proposed models that described direction discrimination thresholds for rotational and translational motions based on the dynamics of the vestibular sensory organs (otoliths and semi-circular canals). As these models have the potential to describe RT for different motion profiles (e.g., trapezoidal versus triangular acceleration profiles or varying profile durations), we validated these models by measuring RTs in human observers for a direction discrimination task using both translational and rotational motions varying in amplitude, duration and acceleration profile shape in a within-subjects design. In agreement with previous studies, amplitude and duration were found to affect RT, and importantly, we found an influence of the profile shape on RT. The models are able to fit the measured RTs with an accuracy of around 5 ms, and the best-fitting parameters are similar to those found from identifying the models based on threshold measurements. This confirms the validity of the modeling approach and links perceptual thresholds to RT. By establishing a link between vestibular thresholds for self-motion and RT, we show for the first time that RTs to purely inertial motion stimuli can be used as an alternative to threshold measurements for identifying self-motion perception models. This is advantageous, since RT tasks are less challenging for participants and make assessment of vestibular function less fatiguing. Further, our results provide strong evidence that the perceived timing of self-motion stimulation is largely influenced by the response dynamics of the vestibular sensory organs.nonotspecifiedhttp://www.cyberneum.de/published11Temporal processing of self-motion: modeling reaction times for rotations and translations1501715422LinkenaugerLBM20133SALinkenaugerMLeyrerHHBülthoffBJMohler2013-07-0078116PLoS ONEThe notion of body-based scaling suggests that our body and its action capabilities are used to scale the spatial layout of the environment. Here we present four studies supporting this perspective by showing that the hand acts as a metric which individuals use to scale the apparent sizes of objects in the environment. However to test this, one must be able to manipulate the size and/or dimensions of the perceiver’s hand which is difficult in the real world due to impliability of hand dimensions. To overcome this limitation, we used virtual reality to manipulate dimensions of participants’ fully-tracked, virtual hands to investigate its influence on the perceived size and shape of virtual objects. In a series of experiments, using several measures, we show that individuals’ estimations of the sizes of virtual objects differ depending on the size of their virtual hand in the direction consistent with the body-based scaling hypothesis. Additionally, we found that these effects were specific to participants’ virtual hands rather than another avatar’s hands or a salient familiar-sized object. While these studies provide support for a body-based approach to the scaling of the spatial layout, they also demonstrate the influence of virtual bodies on perception of virtual environments.nonotspecifiedhttp://www.cyberneum.de/published15Welcome to Wonderland: The Influence of the Size and Shape of a Virtual Hand On the Perceived Size and Shape of Virtual Objects1501715422ChuangNB20137LLChuangFMNieuwenhuizenHHBülftoffLas Vegas, NV, USA2013-07-009510410th International Conference EPCE 2013, Held as Part of HCI International 2013Here, a descriptive study is reported that addresses the relationship between flight control performance and instrument scanning behavior. This work was performed in a fixed-based flight simulator. It targets the ability of untrained novices to pilot a lightweight rotorcraft in a flight scenario that consisted of fundamental mission task elements such as speed and altitude changes. The results indicate that better control performance occurs when gaze is more selective for and focused on key instruments. Ideal instrument scanning behavior is proposed and its relevance for training instructions and visual instrument design is discussed.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/HCI-I-2013-Chuang.pdfpublished9A Fixed-Based Flight Simulator Study: The Interdependence of Flight Control Performance and Gaze Efficiency1501715422VenrooijPMvB20127JVenrooijMDPavelMMulderFCTvan der HelmHHBülthoffAmsterdam, Netherlands2013-07-0084285438th European Rotorcraft Forum (ERF 2012)Biodynamic feedthrough (BDFT) occurs when vehicle vibrations and accelerations feed through the pilot’s body and cause involuntary motion of limbs, resulting in involuntary control inputs. BDFT can severely reduce ride comfort, control accuracy and, above all, safety during the operation of rotorcraft. Furthermore, BDFT can cause and sustain Rotorcraft-Pilot Couplings (RPCs). Despite many studies conducted in past decades – both within and outside of the rotorcraft community – BDFT is still a poorly understood phenomenon. The complexities involved in BDFT have kept researchers and manufacturers in the rotorcraft domain from developing robust ways of dealing with its effects. A practical BDFT pilot model, describing the amount of involuntary control inputs as a function of accelerations, could pave the way to account for adversive
BDFT effects. In the current paper, such a model is proposed. Its structure is based on the model proposed by
Mayo [1], its accuracy and usability are improved by incorporating insights from recently obtained experimental data. An evaluation of the model performance shows that the model describes the measured data well and that it provides a considerable improvement to the original Mayo model. Furthermore, the results indicate that the neuromuscular dynamics have an important influence on the BDFT model parameters.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/ERF-2012-Venrooij-096.pdfpublished12A practical biodynamic feedthrough model for helicopters1501715422AntonelliACR20137GAntonelliFArrichielloSChiaveriniPRobuffo GiordanoWollongong, NSW, Australia2013-07-0013371342IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM 2013)The paper presents an adaptive trajectory tracking control strategy for quadrotor Micro Aerial Vehicles. The proposed approach, while keeping the typical assumption of an orientation dynamics faster than the translational one, removes that of absence of external disturbances and of perfect symmetry of the vehicle. In particular, the trajectory tracking control law is made adaptive with respect to the presence of external forces and moments, and to the uncertainty of dynamic parameters as the position of the center of mass of the vehicle. A stability analysis as well as numerical simulations are provided to support the control design.nonotspecifiedhttp://www.cyberneum.de/published5Adaptive trajectory tracking for quadrotor MAVs in presence of parameter uncertainties and external disturbances1501715422BiegBC20137H-JBiegHHBülthoffLLChuangLas Vegas, NV, USA2013-07-0021274th International Conference DHM 2013, Held as Part of HCI International 2013In the current study, we examine eye movements of human operators during a combined steering and discrimination task. In this task, observers had to alternate their gaze between a central steering task and a discrimination task in the periphery. Our results show that the observer’s gaze behavior is influenced by the motion direction of the steering task. Saccade reaction times (SRTs) of saccades to the discrimination target were shorter if the target appeared in the steering direction. SRTs back to the steering task were shorter when the steering target moved away from the discrimination target. These effects are likely the result of motion-related attention shifts and an interaction of the saccadic and smooth pursuit eye movement system.nonotspecifiedhttp://www.cyberneum.de/published6Attentional Biases during Steering Behavior1501715422ZelazoFABR20127DZelazoAFranchiPAllgöwerHHBülthoffPRobuffo GiordanoSydney, Australia2013-07-004734802012 Robotics: Science and Systems ConferenceRigidity of formations in multi-robot systems is important for formation control, localization, and sensor
fusion. This work proposes a rigidity maintenance gradient controller for a multi-agent robot team. To develop
such a controller, we first provide an alternative characterization of the rigidity matrix and use that
to introduce the novel concept of the rigidity eigenvalue. We provide a necessary and sufficient condition
relating the positivity of the rigidity eigenvalue to the rigidity of the formation. The rigidity maintenance
controller is based on the gradient of the rigidity eigenvalue with respect to each robot position. This gradient has a naturally distributed structure, and is thus amenable to a distributed implementation. Additional
requirements such as obstacle and inter-agent collision avoidance, as well as typical constraints such as
limited sensing/communication ranges and line-of-sight occlusions, are also explicitly considered. Finally,
we present a simulation with a group of seven quadrotor UAVs to demonstrate and validate the theoretical results.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/2012g-ZelFranchiAlgBueRob-preprint.pdfpublished7Rigidity Maintenance Control for Multi-Robot Systems1501715422VolkovaMB20137EPVolkovaBJMohlerHHBülthoffNaples, FL, USA2013-07-0019513th Annual Meeting of the Vision Sciences Society (VSS 2013)People are remarkably good at detecting familiarity with actor (Loula et al., 2005), recognizing the gender (Pollick et al., 2005), emotions (Atkinson et al., 2004) and actions of an actor when presented as biological motion. For many of these tasks the influence of the type of stimuli display (point light display, virtual avatar, full light video) on participants' performance has been well researched (McDonnell et al., 2009). The effect of the size of the display, however, remains underinvestigated. According to our hypothesis, a naturalistic environment and stimuli display would enhance performance, in particular for challenging tasks. We motion captured eight actors, who were asked to portray the following ten emotions while seated: amusement, anger, disgust, fear, joy, pride, relief, sadness, shame, and surprise. The resulting 80 motion sequences were then applied to a stick figure and used for the emotion recognition study. As a between participant factor, the stick figure animations were presented either on a laptop screen or on a large back projection surface. In the latter condition the size of the stick figure matched the natural size of the actors. Thirty-two participants (16 female) took part in a between-subject study (gender balanced). For each stimulus the participant had to make a ten-alternative forced choice to categorize the animation as one of ten emotions. Recognition accuracy was significantly higher for natural size condition (38% accuracy for back projection condition vs. 31% for desktop), and reaction time was lower (2.3 animation repetitions for back projection condition vs. 2.7 for desktop condition). In both conditions the emotional categories were an important factor as some emotions were more easily recognized than others. The results show that for complex tasks, e.g. discrimination among multiple emotional categories, enhanced naturalness of stimuli can be beneficiary for the observer.nonotspecifiedhttp://www.cyberneum.de/published-195Display size of biological motion stimulus influences performance in a complex emotional categorisation task1501715422JungBTLA20137W-MJungIBülthoffIThorntonS-WLeeRArmannNaples, FL, USA2013-07-0086113th Annual Meeting of the Vision Sciences Society (VSS 2013)One possibility to overcome the processing limitation of the visual system is to attend selectively to relevant information only. Another strategy is to process sets of objects as ensembles and represent their average characteristics instead of individual group members (e.g., mean size, brightness, orientation). Recent evidence suggests that ensemble representation might occur even for human faces (for a summary, see Alvarez, 2011), i.e., observers can extract the mean emotion, sex, and identity from a set of faces (Habermann & Whitney, 2007; de Fockert & Wolfenstein, 2009). Here, we extend this line of research into the realm of face race: Can we extract the "mean race" of a set of faces when no conscious perception of single individuals is possible? Moreover, does the visual system process own- and other-race faces differently at this stage? Face stimuli had the same (average) male identity but were morphed, at different levels, in between Asian and Caucasian appearance. Following earlier studies (e.g., Habermann & Whitney, 2007, 2010), observers were briefly (250ms) presented with random sets of 12 of these faces. They were then asked to adjust a test face to the perceived mean race of the set by "morphing" it between Asian and Caucasian appearance. The results show that for most participants the response error distribution is significantly different from random, while their responses are centered around the real stimulus set mean - suggesting that they are able to extract "mean race". Also, we find a bias towards responding more "Asian" than the actual mean of a face set. All participants tested so far are South Korean (from Seoul), indicating that even at this early (unconscious) processing stage, the visual system distinguishes between own- and other-race faces, giving more weight to the former. Follow-up experiments on Caucasian participants will be performed to validate this observation.nonotspecifiedhttp://www.cyberneum.de/published-861The Role of Race in Summary Representations of Faces1501715422delaRosaSGBC201310Sde la RosaSStreuberMGieseHHBülthoffCCurioBulthoff2013_510HHBülthoffFranchi2013_410AFranchiBulthoff2013_410HHBülthoffBulthoff2013_310HHBülthoffPretto2013_210PPrettonooij201310SNooijBulthoff2013_210HHBülthoffpariseE201310CVPariseMOErnstPretto201310PPrettoPariseKE20137CVPariseKKnorreMOErnstJerusalem, Israel2013-06-0419014th International Multisensory Research Forum (IMRF 2013)The association between auditory pitch and spatial elevation is one the most fascinating examples of cross-dimensional mappings: in a wide range of cognitive, perceptual, attentional and linguistic tasks, humans consistently display a positive, sometimes absolute, association between auditory pitch and spatial elevation. However, the origins of such a pervasive mapping are still largely unknown. Through a combined analysis of environmental sounds and anthropometric measures, we demonstrate that, statistically speaking, this mapping is already present in both the distal and the proximal stimulus. Specifically, in the environment, high sounds are more likely to come from above; moreover, due to the filtering properties of the external ear, sounds coming from higher elevations have more energy at high frequencies. Next, we investigated whether the internalized mapping depends on the statistics of the proximal, or of the distal stimulus. In a psychophysical task, participants had to localize narrow band-pass noises with different central frequencies, while head- and world-centred reference frames were put into conflict by tilting participants’ body orientation. The frequency of the sounds systematically biased localization in both head- and world-centred coordinates, and, remarkably, in agreement with the mappings measured in both the distal and proximal stimulus. These results clearly demonstrate that the cognitive mapping between pitch and elevation mirror the statistical properties of the auditory signals. We argue that, in a shorter time-scale, humans learn the statistical properties auditory signals; while, in a longer timescale, the evolution of the acoustic properties of the external ear itself is shaped by the statistics of the acoustic environment.nonotspecifiedhttp://www.cyberneum.de/published-190On pitch-elevation mapping: Nature, nurture and behaviour1501715422SennaMBP20137ISennaAMaravitaNBologniniCVPariseJerusalem, Israel2013-06-0420314th International Multisensory Research Forum (IMRF 2013)Our body is made of flesh and bones. We know it, and in our daily lives all the senses – including touch, vision, and audition – constantly provide converging information about this simple, factual truth. But is this necessarily always the case? Here we report a surprising bodily illusion demonstrating that human observers rapidly update their assumptions about the material qualities of their body, based on their recent multisensory perceptual experience. To induce an illusory misperception of the material properties of the hand, we repeatedly gently hit participants’ hand, while progressively replacing the natural sound of the hammer against the skin with the sound of a hammer hitting a piece of marble. After five minutes, the hand started feeling stiffer, heavier, harder, less sensitive, and unnatural, and showed enhanced Galvanic skin response to threatening stimuli. This novel bodily illusion, the ’Marble-Hand Illusion’, demonstrates that the experience of the material of our body, surely the most stable attribute of our bodily self, can be quickly updated through multisensory integration.nonotspecifiedhttp://www.cyberneum.de/published-203The marble-hand illusion1501715422Curio2013_210CCurioNieuwenhuizenB20133FMNieuwenhuizenHHBülthoff2013-06-0027122131Journal of Computing Science and EngineeringThe MPI CyberMotion Simulator provides a unique motion platform, as it features an anthropomorphic robot with a large workspace, combined with an actuated cabin and a linear track for lateral movement. This paper introduces the simulator as a tool for studying human perception, and compares its characteristics to conventional Stewart platforms. Furthermore, an experimental evaluation is presented in which multimodal human control behavior is studied by identifying the visual and vestibular responses of participants in a roll-lateral helicopter hover task. The results show that the simulator motion allows participants to increase tracking performance by changing their control strategy, shifting from reliance on visual error perception to reliance on simulator motion cues. The MPI CyberMotion Simulator has proven to be a state-of-the-art motion simulator for psychophysical research to study humans with various experimental paradigms, ranging from passive perception experiments to active control tasks, such as driving a car or flying a helicopter.nonotspecifiedhttp://www.cyberneum.de/published9The MPI CyberMotion Simulator: A Novel Research Platform to Investigate Human Control Behavior1501715422HerdtweckC20137CHerdtweckCCurioGold Coast, Australia2013-06-00403410IEEE Intelligent Vehicles Symposium (IV 2013)Determining the viewpoint of traffic participants provides valuable high-level attributes to constrain the interpretation of their movement, and thus allows more specific predictions of alert behavior. We present a monocular object viewpoint estimation approach that is realized by a random regression forest. In particular, we address the circular and continuous structure of the problem for training the decision trees. Our approach builds on a 2D deformable part based object detector. Using detected cars on the KITTI vision benchmark, we demonstrate performance for continuous viewpoint estimation, ground point estimation, and their integration into a high-dimensional particle filtering framework. Besides location and viewpoint of cars, the filter framework considers full monocular egomotion information of the observing platform. This demonstrates the versatility of using only monocular information processing with appropriate machine learning.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/IV-2013-Herdtweck-Curio.pdfpublished7Monocular Car Viewpoint Estimation with Circular Regression Forests1501715422Mohler2013_310BMohlerMohler2013_210BMohlerStefanucciGGC201310JStefanucciMGeussKGagnonSCreem-RegehrGillespieL201310TGillespieMLiebschBulthoff2013_610IBülthoffZhaoW201310MZhaoWHWarrenMeilinger2013_210TMeilingerBulthoffTK2013HHBülthoffHTeufelMKerger2013-05-02The invention relates to a motion simulator for simulating a motion of a vehicle, particularly an aircraft, comprising: a multi-axis serial robot (1) comprising a rotatable base axis (2), and a seat (17) for an operator, wherein the seat (17) is attached to the multi-axis serial robot (1), so that the seat (17) can be moved in space by the multi-axis serial robot (1) for simulation of a real movement, wherein the motion simulator is adapted to simulate a long-lasting acceleration or deceleration by generating a centrifugal force acting on the operator. Further, the invention relates to a corresponding method.nonotspecifiedhttp://www.cyberneum.de/publishedMotion simulator and corresponding method1501715422BonevCE20123BBonevLLChuangFEscolano2013-05-00734723–730Pattern Recognition LettersIn this paper we propose an information-theoretic approach to understand eye-movement patterns, in relation to the task performed and image complexity. We commence with the analysis of the distributions and amplitudes of eye-movement saccades, performed across two different image-viewing tasks: free viewing and visual search. Our working hypothesis is that the complexity of image information and task demands should interact. This should be reflected in the Markovian pattern of short and long saccades. We compute high-order Markovian models of performing a large saccade after many short ones and also propose a novel method for quantifying image complexity. The analysis of the interaction between high-order Markovianity, task and image complexity supports our hypothesis.nonotspecifiedhttp://www.cyberneum.de/published-723How do image complexity, task demands and looking biases influence human gaze behavior?1501715422NieuwenhuizenMvB20133FMNieuwenhuizenMMulderMMvan PaassenHHBülthoff2013-05-00336667676Journal of Guidance, Control, and DynamicsLow-cost motion systems have been proposed for certain training tasks that would otherwise be performed on highperformance full-flight simulators. These systems usually have lower bandwidth and lower smoothness. The influence of these characteristics on pilot perception and control behavior is unknown and needs to be investigated. In this paper, this is done by simulating a model of a simulator with limited capabilities on a high-end simulator. The platform limitations, which consist of a platform filter, time delay, and noise characteristics, can then be removed one by one, and their effect on control behavior is studied in isolation. An experiment was conducted to identify pilot perception and control behavior in a closed-loop control task. The time delay and noise characteristics of the simulators did not have an effect. However, it was found that the bandwidth of the motion system had a significant effect on performance and control behavior. Results indicate that the motion cues were barely used at all in conditions with a low bandwidth, and that participants relied on the visual cues to generate lead to perform the control task.nonotspecifiedhttp://www.cyberneum.de/published9Influences of Simulator Motion System Characteristics on Pilot Control Behavior1501715422WallravenWB20133CWallravenLWhittingstallHHBülthoff2013-05-004226513523Experimental Brain ResearchHuman observers are experts at visual face recognition due to specialized visual mechanisms for face processing that evolve with perceptual expertize. Such expertize has long been attributed to the use of configural processing, enabled by fast, parallel information encoding of the visual information in the face. Here we tested whether participants can learn to efficiently recognize faces that are serially encoded—that is, when only partial visual information about the face is available at any given time. For this, ten participants were trained in gaze-restricted face recognition in which face masks were viewed through a small aperture controlled by the participant. Tests comparing trained with untrained performance revealed (1) a marked improvement in terms of speed and accuracy, (2) a gradual development of configural processing strategies, and (3) participants’ ability to rapidly learn and accurately recognize novel exemplars. This performance pattern demonstrates that participants were able to learn new strategies to compensate for the serial nature of information encoding. The results are discussed in terms of expertize acquisition and relevance for other sensory modalities relying on serial encoding.nonotspecifiedhttp://www.cyberneum.de/published10Learning to recognize face shapes through serial exploration1501715422RuddleVB20133RARuddleEVolkovaHHBülthoff2013-05-002:1110111ACM Transactions on Applied PerceptionThis article provides longitudinal data for when participants learned to travel with a walking metaphor through virtual reality (VR) worlds, using interfaces that ranged from joystick-only, to linear and omnidirectional treadmills, and actual walking in VR. Three metrics were used: travel time, collisions (a measure of accuracy), and the speed profile. The time that participants required to reach asymptotic performance for traveling, and what that asymptote was, varied considerably between interfaces. In particular, when a world had tight turns (0.75 m corridors), participants who walked were more proficient than those who used a joystick to locomote and turned either physically or with a joystick, even after 10 minutes of training. The speed profile showed that this was caused by participants spending a notable percentage of the time stationary, irrespective of whether or not they frequently played computer games. The study shows how speed profiles can be used to help evaluate participants' proficiency with travel interfaces, highlights the need for training to be structured to addresses specific weaknesses in proficiency (e.g., start-stop movement), and for studies to measure and report that proficiency.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/ruddle-acm-tap.pdfpublished10Learning to Walk in Virtual Reality1501715422BerthozBBCFFHKMMNPRSSTVvVW20133ABerthozWBlesHHBülthoffBJCorreia GracioPFeenstraNFilliardRHuhneAKemenyMMayrhoferMMulderHGNusseckPPrettoGReymondRSchlüsselbergerJSchwandtnerHTeufelBVailleauMMvan PaassenMVidalMWentink2013-05-00343265276IEEE Transactions on Human-Machine SystemsAdvanced driving simulators aim at rendering the motion of a vehicle with maximum fidelity, which requires increased mechanical travel, size, and cost of the system. Motion cueing algorithms reduce the motion envelope by taking advantage of limitations in human motion perception, and the most commonly employed method is just to scale down the physical motion. However, little is known on the effects of motion scaling on motion perception and on actual driving performance. This paper presents the results of a European collaborative project, which explored different motion scale factors in a slalom driving task. Three state-of-the-art simulator systems were used, which were capable of generating displacements of several meters. The results of four comparable driving experiments, which were obtained with a total of 65 participants, indicate a preference for motion scale factors below 1, within a wide range of acceptable values (0.4–0.75). Very reduced or absent motion cues significantly degrade driving performance. Applications of this research are discussed for the design of motion systems and cueing algorithms for driving simulation.nonotspecifiedhttp://www.cyberneum.de/published11Motion Scaling for High-Performance Driving Simulators1501715422SchultzBBP20123JSchultzMBrockhausHHBülthoffKPilz2013-05-0052311671178Cerebral CortexFacial motion carries essential information about other people's emotions and intentions. Most previous studies have suggested that facial motion is mainly processed in the superior temporal sulcus (STS), but several recent studies have also shown involvement of ventral temporal face-sensitive regions. Up to now, it is not known whether the increased response to facial motion is due to an increased amount of static information in the stimulus, to the deformation of the face over time, or to increased attentional demands. We presented nonrigidly moving faces and control stimuli to participants performing a demanding task unrelated to the face stimuli. We manipulated the amount of static information by using movies with different frame rates. The fluidity of the motion was manipulated by presenting movies with frames either in the order in which they were recorded or in scrambled order. Results confirm higher activation for moving compared with static faces in STS and under certain conditions in ventral temporal face-sensitive regions. Activation was maximal at a frame rate of 12.5 Hz and smaller for scrambled movies. These results indicate that both the amount of static information and the fluid facial motion per se are important factors for the processing of dynamic faces.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/Cerebral-Cortex-2012-Schultz.pdfpublished11What the Human Brain Likes About Facial Motion1501715422HongBS20137AHongHHBülthoffHISonKarlsruhe, Germany2013-05-0014711478IEEE International Conference on Robotics and Automation (ICRA 2013)For teleoperation of multiple mobile robots (e.g., unmanned aerial vehicles), a better situational awareness of remote environments is crucial for good performance. Visual and force feedback are the most common ways to perceive the environments accurately using a vision system and a haptic device, respectively. In outdoor environments, however, it is difficult to use adequate/accurate sensors (e.g., global localization system) for haptic feedback of the remote environments as well as the slave robots. In this paper, we propose a visual and force feedback method to enhance a human operator's situational awareness in multi-robot teleoperation by fabricating a global view of the multi-robot system and transmitting velocity information of one, respectively, using only local information of the robots. The proposed visual feedback method, then, is evaluated via two psychophysical experiments: maneuvering and searching tests. Several measures are also proposed to assess the human operator's maneuverability and situational awareness quantitatively.nonotspecifiedhttp://www.cyberneum.de/published7A visual and force feedback for multi-robot teleoperation in outdoor environments: A preliminary result1501715422SecchiFBR20137CSecchiAFranchiHHBülthoffPRobuffo GiordanoKarlsruhe, Germany2013-05-0036453652IEEE International Conference on Robotics and Automation (ICRA 2013)This paper presents a novel bilateral controller that allows to stably teleoperate the degree of connectivity in the mutual interaction between a remote group of mobile robots considered as the slave-side. A distributed leader-follower scheme allows the human operator to command the overall group motion. The group autonomously maintains the connectivity of the interaction graph by using a decentralized gradient descent approach applied to the Fiedler eigenvalue of a properly weighted Laplacian matrix. The degree of connectivity, and then the flexibility, of the interaction graph can be finely tuned by the human operator through an additional bilateral teleoperation channel. Passivity of the overall system is theoretically proven and extensive human/hardware in-the-loop simulations are presented to empirically validate the theoretical analysis.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/2013d-SecFraBueRob.pdfpublished7Bilateral Control of the Degree of Connectivity in Multiple Mobile-robot Teleoperation1501715422DropPvMB20137FMDropDMPoolMMvan PaassenMMulderHHBülthoffPhoenix, AZ, USA2013-05-001797181169th American Helicopter Society International Annual Forum (AHS 2013)Pure feedback and pure open-loop feedforward helicopter pi
lot models are currently applied for predicting the performance of pilot-helicopter systems. We argue that feedback models are likely to underestimate performance in many realistic helicopter maneuvers, whereas inverse simulation models, which have an open-loop feedforward structure, are likely to overestimate performance as they neglect typical human-in-the-loop characteristics. True verification of feedback and feedforward elements in helicopter pilot control behavior was never performed, however. This paper proposes a pilot model containing a feedback and feedforward controller acting simultaneously and presents a method to identify the hypothesized feedforward action from human-in-the-loop data collected in a simulator experiment. The results of the human-in-the-loop experiment show that actual human performance is better than predicted by a pure feedback model and worse than predicted by an (inverse dynamics) feedforward model. The identification results suggest that the human pilot indeed utilizes feedforward strategies, but it was not possible to either confirm or refute the model by means of the collected data and the developed analysis method.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/AHS-2013-Drop.pdfpublished14Feedforward and Feedback Control Behavior in Helicopter Pilots during a Lateral Reposition Task1501715422RyllBR20137MRyllHHBülthoffPRobuffo GiordanoKarlsruhe, Germany2013-05-00295302IEEE International Conference on Robotics and Automation (ICRA 2013)In this work we present a novel concept of a quadrotor UAV with tilting propellers. Standard quadrotors are limited in their mobility because of their intrinsic underactuation (only 4 independent control inputs vs. their 6-dof pose in space). The quadrotor prototype discussed in this paper, on the other hand, has the ability to also control the orientation of its 4 propellers, thus making it possible to overcome the aforementioned underactuation and behave as a fully-actuated flying vehicle. We first illustrate the hardware/software specifications of our recently developed prototype, and then report the experimental results of some preliminary, but promising, flight tests which show the capabilities of this new UAV concept.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/ICRA-2013-Ryll.pdfpublished7First Flight Tests for a Quadrotor UAV with Tilting Propellers1501715422NestmeyerRLHBRF20137TNestmeyerMRiedelJLächeleSHartmannFBotschenPRobuffo GiordanoAFranchiKarlsruhe, Germany2013-05-0013ICRA 2013 Workshop Towards Fully Decentralized Multi-Robot Systems: Hardware, Software and Integrationnonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/ICRA-2013-Workshop-Nestmeyer.pdfpublished2Interactive Demo: Haptic Remote Control of Multiple UAVs with Autonomous Cohesive Behavior1501715422LacheleRRF20137JLächeleMRiedelPRobuffo GiordanoAFranchiKarlsruhe, Germany2013-05-0013ICRA 2013 Workshop Towards Fully Decentralized Multi-Robot Systems: Hardware, Software and IntegrationIn this notes we briefly review two software frameworks that have been developed within the Autonomous Robotics and Human-machine Systems group (formerly, Human-Robot Interaction group) at the Max Plank Institute for Biological Cybernetics. Both frameworks, starting from
the early versions up to the most recent releases, have
been successfully employed in several works of the group,
including, e.g., [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12]. For a detailed description of SwarmSimX, we refer the interested reader to [13], [14]. The TeleKyb framework is instead described thoroughly in [15] and available at http://www.ros.org/wiki/telekyb.
.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/ICRA-2013-Workshop-Laechele.pdfpublished2SwarmSimX and TeleKyb: Two ROS-integrated Software Frameworks for Single- and Multi-Robot Applications1501715422FranchiR201310AFranchiPRobuffo GiordanoNestmeyerRF201310TNestmeyerPRobuffo GiordanoAFranchiFranchi2013_310AFranchiPiryankovadKBM20133IVPiryankovaSde la RosaUKloosHHBülthoffBJMohler2013-04-00234153–164DisplaysMany scientists have demonstrated that compared to the real world egocentric distances in head-mounted display virtual environments are underestimated. However, distance perception in large screen immersive displays has received less attention. We investigate egocentric distance perception in a virtual office room projected using a semi-spherical, a Max Planck Institute CyberMotion Simulator cabin and a flat large screen immersive display. The goal of our research is to systematically investigate distance perception in large screen immersive displays with commonly used technical specifications. We specifically investigate the role of distance to the target, stereoscopic projection and motion parallax on distance perception. We use verbal reports and blind walking as response measures for the real world experiment. Due to the limited space in the three large screen immersive displays we use only verbal reports as the response measure for the experiments in the virtual environment. Our results show an overall underestimation of distance perception in the large screen immersive displays, while verbal estimates of distances are nearly veridical in the real world. We find that even when providing motion parallax and stereoscopic depth cues to the observer in the flat large screen immersive display, participants estimate the distances to be smaller than intended. Although stereo cues in the flat large screen immersive display do increase distance estimates for the nearest distance, the impact of the stereoscopic depth cues is not enough to result in veridical distance perception. Further, we demonstrate that the distance to the target significantly influences the percent error of verbal estimates in both the real and virtual world. The impact of the distance to the target on the distance judgments is the same in the real world and in two of the used large screen displays, namely, the MPI CyberMotion Simulator cabin and the flat displays. However, in the semi-spherical display we observe a significantly different influence of distance to the target on verbal estimates of egocentric distances. Finally, we discuss potential reasons for our results. Based on the findings from our research we give general suggestions that could serve as methods for improving the LSIDs in terms of the accuracy of depth perception and suggest methods to compensate for the underestimation of verbal distance estimates in large screen immersive displays.nonotspecifiedhttp://www.cyberneum.de/published-153Egocentric distance perception in large screen immersive displays1501715422SonFLKBR20123HISonAFranchiLLChuangJKimHHBülthoffPRobuffo Giordano2013-04-00243597609IEEE Transactions on CyberneticsIn this paper, we investigate the effect of haptic cueing on a human operator's performance in the field of bilateral teleoperation of multiple mobile robots, particularly multiple unmanned aerial vehicles (UAVs). Two aspects of human performance are deemed important in this area, namely, the maneuverability of mobile robots and the perceptual sensitivity of the remote environment. We introduce metrics that allow us to address these aspects in two psychophysical studies, which are reported here. Three fundamental haptic cue types were evaluated. The Force cue conveys information on the proximity of the commanded trajectory to obstacles in the remote environment. The Velocity cue represents the mismatch between the commanded and actual velocities of the UAVs and can implicitly provide a rich amount of information regarding the actual behavior of the UAVs. Finally, the Velocity+Force cue is a linear combination of the two. Our experimental results show that, while maneuverability is best supported by the Force cue feedback, perceptual sensitivity is best served by the Velocity cue feedback. In addition, we show that large gains in the haptic feedbacks do not always guarantee an enhancement in the teleoperator's performance.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/2013a-SonFraChuKimBueRob.pdfpublished12Human-Centered Design and Evaluation of Haptic Cueing for Teleoperation of Multiple Mobile Robots1501715422ZaalNvM20133PMTZaalFMNieuwenhuizenMMvan PaassenMMulder2013-04-00243544556IEEE Transactions on CyberneticsIn this paper, we investigate the effects of visual and motion stimuli on the manual control of one's direction of self-motion. In a flight simulator, subjects conducted an active target-following disturbance-rejection task, using a compensatory display. Simulating a vehicular control task, the direction of vehicular motion was shown on the outside visual display in two ways: an explicit presentation using a symbol and an implicit presentation, namely, through the focus of radial outflow that emerges from optic flow. In addition, the effects of the relative strength of congruent vestibular motion cues were investigated. The dynamic properties of human visual and vestibular motion perception paths were modeled using a control-theoretical approach. As expected, improved tracking performance was found for the configurations that explicitly showed the direction of self-motion. The human visual time delay increased with approximately 150 ms for the optic flow conditions, relative to explicit presentations. Vestibular motion, providing higher order information on the direction of self-motion, allowed subjects to partially compensate for this visual perception delay, improving performance. Parameter estimates of the operator control model show that, with vestibular motion, the visual feedback becomes stronger, indicating that operators are more confident to act on optic flow information when congruent vestibular motion cues are present.nonotspecifiedhttp://www.cyberneum.de/published12Modeling Human Control of Self-Motion Direction With Optic Flow and Vestibular Motion1501715422CensiFMO20123ACensiAFranchiLMarchionniGOriolo2013-04-00229475492IEEE Transaction on RoboticsConsider a differential-drive mobile robot equipped with an on-board exteroceptive sensor that can estimate its own motion, e.g., a range-finder. Calibration of this robot involves estimating six parameters: three for the odometry (radii and distance between the wheels) and three for the pose of the sensor with respect to the robot. After analyzing the observability of this problem, this paper describes a method for calibrating all parameters at the same time, without the need for external sensors or devices, using only the measurement of the wheel velocities and the data from the exteroceptive sensor. The method does not require the robot to move along particular trajectories. Simultaneous calibration is formulated as a maximum-likelihood problem and the solution is found in a closed form. Experimental results show that the accuracy of the proposed calibration method is very close to the attainable limit given by the Cramér-Rao bound.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/2013i-CenFraMarOri.pdfpublished17Simultaneous Calibration of Odometry and Sensor Parameters for Mobile Robots1501715422Franchi201310AFranchiEndresANG20137DMEndresRAdamUNoppeneyMAGieseGöttingen, Germany2013-03-131016101710th Göttingen Meeting of the German Neuroscience Society, 34th Göttingen Neurobiology ConferenceUnderstanding how semantic information is represented in the brain has been an important research
focus of neuroscience in the past few years. Unlike 'traditional' neural (de)coding approaches, which
study the relationship between stimulus and neural response, we are interested in higher-order relational
coding: we ask how perceived relationships between stimuli (e.g. similarity) are connected to
corresponding relationships in the neural activity. Our approach addresses the semantical problem, i.e.
how terms (here stimuli) come to have their (possibly subjective) meaning, from the perspective of the
network theory of semantics (Churchland 1984). This theory posits that meaning arises from the network
of concepts within which a given term is embedded.
We showed previously (Endres et al 2010, AMAI) that Formal Concept Analysis (FCA, (Ganter & Wille
1999)) can reveal interpretable semantic information (e.g. specialization hierarchies, or feature-based
representation) from electrophysiological data. Unlike other analysis methods (e.g. hierarchical
clustering), FCA does not impose inappropriate structure on the data. FCA is a mathematical formulation
of the explicit coding hypothesis (Foldiak, 2009, Curr. Biol.)
Here, we investigate whether similar findings can be obtained from fMRI BOLD responses recorded from
human subjects. While the BOLD response provides only an indirect measure of neural activity on a
much coarser spatio-temporal scale than electrophysiological recordings, it has the advantage that it can
be recorded from humans, which can be questioned about their perceptions during the experiment,
thereby obviating the need of interpreting animal behavioural responses. Furthermore, the BOLD signal
can be recorded from the whole brain simultaneously.
In our experiment, a single human subject was scanned while viewing 72 grayscale pictures of animate
and inanimate objects in a target detection task (Siemens Trio 3T scanner, GE-EPI, TE=40ms, 38 axial
slices, TR=3.08s, 48 sessions, amounting to a total of 10,176 volume images). These pictures comprise
the formal objects for FCA. We computed formal attributes by learning a hierarchical Bayesian classifier,
which maps BOLD responses onto binary features, and these features onto object labels. The
connectivity matrix between the binary features and the object labels can then serve as the formal
context.
In line with previous reports, FCA revealed a clear dissociation between animate and inanimate objects in
a high-level visual area (inferior temporal cortex, IT), with the inanimate category including plants. The
inanimate category was subdivided into plants and non-plants when we increased the number of
attributes extracted from the fMRI responses. FCA also highlighted organizational differences between
the IT and the primary visual cortex, V1. We show that subjective familiarity and similarity ratings are
strongly correlated with the attribute structure computed from the fMRI signal (Endres et al. 2012,
ICFCA).nonotspecifiedhttp://www.cyberneum.de/published1Connecting Brain and Mind with Formal Concept Analysis: a Data-Driven Investigation of the Semantic, Explicit Coding Hypothesis15017154221501718826Franchi2013_210AFranchiMeilinger2013_310TMeilingerCurio201310CCurioRobuffoGiordanoFSB20123PRobuffo GiordanoAFranchiCSecchiHHBülthoff2013-03-00332299323International Journal of Robotics ResearchThe design of decentralized controllers coping with the typical constraints on the inter-robot sensing/communication capabilities represents a promising direction in multi-robot research thanks to the inherent scalability and fault tolerance of these approaches. In these cases, connectivity of the underlying interaction graph plays a fundamental role: it represents a necessary condition for allowing a group or robots to achieve a common task by resorting to only local information. The goal of this paper is to present a novel decentralized strategy able to enforce connectivity maintenance for a group of robots in a flexible way, that is, by granting large freedom to the group internal configuration so as to allow establishment/deletion of interaction links at anytime as long as global connectivity is preserved. A peculiar feature of our approach is that we are able to embed into a unique connectivity preserving action a large number of constraints and requirements for the group: (i) the presence of specific inter-robot sensing/communication models; (ii) group requirements such as formation control; and (iii) individual requirements such as collision avoidance. This is achieved by defining a suitable global potential function of the second smallest eigenvalue λ2 of the graph Laplacian, and by computing, in a decentralized way, a gradient-like controller built on top of this potential. Simulation results obtained with a group of quadrotor unmanned aerial vehicles (UAVs) and unmanned ground vehicles, and experimental results obtained with four quadrotor UAVs, are finally presented to thoroughly illustrate the features of our approach on a concrete case study.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/2013l-RobFraSecBue-preprint.pdfpublished24A Passivity-Based Decentralized Strategy for Generalized Connectivity Maintenance1501715422KimKLKLCLPC20133H-SKimY-JKimH-JLeeS-YKimHLeeD-SChangHLeeH-JParkYChae2013-03-00201318Evidence-Based Complementary and Alternative MedicineObjectives. Strong aversions to acupuncture have been an obstacle to understanding its intrinsic action of acupuncture. Thus, it is necessary to evaluate the nature and extent of fear of acupuncture treatment. Our study aims to develop and validate an instrument that evaluates a patient’s fear of acupuncture treatment. Methods. We have developed an acupuncture fear scale, a 16-item instrument which assesses the acupuncture fear score and uses it to survey 275 participants in South Korea, thus testing the reliability and validity of the instrument. Results. Internal consistency was high (Cronbach’s alpha = 0.935). Test-retest reliability (Spearman’s rank correlation coefficient) among 33 participants out of 275 ranged from 0.565 to 0.797 (P < 0.001). Principal component analysis revealed two factors accounting for 68% of the variance, which are painful sensation and possible adverse events, respectively. The acupuncture fear scale was positively correlated with the total of fear of pain questionnaire-III (r = 0.423, P < 0.001). Conclusions. The acupuncture fear scale can be a valid and reliable instrument that can measure fear of acupuncture treatment. These results strongly suggest that it would be a clinically useful tool to assess fear of acupuncture in the acupuncture clinic setting and an important instrument to understand the complex social-behavioral component of acupuncture modality.nonotspecifiedhttp://www.cyberneum.de/published7Development and Validation of Acupuncture Fear Scale1501715422ChoSBLL20113JHChoHISonTBhattacharjeeDGLeeDYLee2013-03-00360946957IEEE Transactions on Industrial ElectronicsSurgical teleoperation systems are being increasingly deployed recently. There are, however, some unsolved issues such as nonlinear characteristics of the interaction between the slave robot and soft tissues, and difficulty in employing force sensors in the surgical end-effectors of the slave. These issues make it difficult to generalize any approach to develop a control for the system. This paper addresses these issues by proposing a H1 suboptimal controller preserving robust stability and performance. The environment, i.e., soft tissues, is characterized with the nonlinear Hunt-Crossley model. This nonlinear characteristics of soft tissues are expressed with an affine combination of linear models within a predefined parameter polytope. For this linear parmeter varying system, a gain-scheduling control scheme is employed to design a sub-optimal controller while guaranteeing its stability. To avoid using any force measurement in slave, we used position-position control architecture. The developed gain-scheduling control is validated with quantitative experimental results. The developed gain-scheduling PP control scheme shows good tracking capacity and high transparency for varied experimental conditions. Error of the transmitted impedance is significantly lower compared to other conventional control schemes for frequencies less than 2Hz which is frequently recommended for surgical teleoperation.nonotspecifiedhttp://www.cyberneum.de/published11Gain-Scheduling Control of Teleoperation Systems Interacting With Soft Tissues1501715422ChangKLLLPWC20133D-SChangY-JKimS-HLeeHLeeI-SLeeH-JParkCWallravenYChae2013-03-00201317Evidence-Based Complementary and Alternative MedicineBackground. The rubber hand illusion (RHI) is an experimental paradigm that manipulates important aspects of body self-awareness. Objectives. We were interested in whether modifying bodily self-awareness by manipulation of body ownership and visual expectations using the RHI would change the subjective perception of pain as well as the autonomic response to acupuncture needle stimulation. Methods. Acupuncture needle stimulation was applied to the real hand during the RHI with (experiment 1) or without (experiment 2) visual expectation while measuring concurrent autonomic changes such as the skin conductance response (SCR). Subjective responses such as perception of the RHI and perceived pain were measured by questionnaires. Results. In experiment 1, the amplitude of the increase in SCR was visibly higher during the synchronous session compared with that of the asynchronous session. In experiment 2, the amplitude of the increase of SCR was lower for the synchronous session compared with that for the asynchronous session. Comparing these two experiments, the visual expectation of needle stimulation produced a greater autonomic response to acupuncture stimulation. Conclusions. Our findings suggest that the sympathetic response to acupuncture needle stimulation is primarily influenced by visual expectation rather than by modifications of body ownership.nonotspecifiedhttp://www.cyberneum.de/published6Modifying Bodily Self-Awareness during Acupuncture Needle Stimulation Using the Rubber Hand Illusion1501715422deLucaMRUSvKv20123ADe LucaRMattonePRobuffo GiordanoHUlbrichMSchwaigerMvan BerghEKoller-MeierLvan Gool2013-03-00221410427IEEE Transactions on Control Systems TechnologyThe CyberCarpet is an actuated platform that allows unconstrained locomotion of a walking user for Virtual Reality exploration. The platform consists of a linear treadmill covered by a ball-array carpet and mounted on a turntable, and is equipped with two actuating devices for linear and angular motion. The main control objective is to keep the walker close to the platform center in the most natural way, counteracting his/her voluntary motion while satisfying perceptual constraints. The motion control problem for this platform is not trivial since the system kinematics is subject to a nonholonomic constraint. In the first part of the paper we describe the kinematic control design devised within the CyberWalk project, where the linear and angular platform velocities are used as input commands and feedback is based only on walker's position measurements obtained by an external visual tracking system. In particular, we present a globally stabilizing control scheme that combines a feedback and a feedforward action, based on a disturbance observer of the walker's intentional velocity. We also discuss possible extensions to acceleration-level control and the related assessment of dynamic issues affecting a walker during his/her motion. The second part of the paper is devoted to the actual implementation of the overall system. As a proof of concept of a final full-scale platform, the mechanical design and realization of a small-scale prototype of the CyberCarpet is presented, as well as the visual localization method used to obtain the human walker's position on the platform by an overhead camera. To validate the proposed motion control design, experimental results are reported and discussed for a series of motion tasks performed using a small tracked vehicle representative of a moving user.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/CyberCarpet_TCST_2011-0582.pdfpublished17Motion Control of the CyberCarpet Platform1501715422SchultzB20133JSchultzHHBülthoff2013-03-004:1513119Journal of VisionIdentifying moving things in the environment is a priority for animals as these could be prey, predators, or mates. When the shape of a moving object is hard to see, motion becomes an important cue to distinguish animate from inanimate things. We report a new stimulus in which a single moving dot evokes a reasonably strong percept of animacy by mimicking the motion of naturally occurring stimuli, with minimal context information. Stimulus movements are controlled by an equation such that changes in a single movement parameter lead to gradual changes in animacy judgments with minimal changes in low-level stimulus properties. An infinite number of stimuli can be created between the animate and inanimate extremes. A series of experiments confirm the strength of the percept and show that observers tend to follow the stimulus with their eye gaze. However, eye movements are not necessary for perceptual judgments, as forced fixation on the display center only slightly reduces the amplitude of percept changes. Withdrawing attentional resources from the animacy judgment using a simultaneous secondary task further reduces percept amplitudes without abolishing them. This stimulus could open new avenues for the principled study of animacy judgments based on object motion only.nonotspecifiedhttp://www.cyberneum.de/published18Parametric animacy percept evoked by a single moving dot mimicking natural stimuli1501715422WallisT20133GWallisJTichon2013-03-001226785PresenceThe quality of a virtual environment, as characterized by factors such as presence and fidelity, is of interest to developers and users of simulators for many reasons, not least because both factors have been linked to improved outcomes in training as well as a reduced incidence of simulator sickness. Until recently, most approaches to measuring these factors have been based on subjective, postexposure questioning. This approach has, however, been criticized because of the shortcomings of self-report and the need to delay feedback or interrupt activity. To combat these problems, recent papers on the topic have proposed the use of behavioral measures to assess simulators and predict training outcomes. Following their lead, this paper makes use of a simple perceptual task in which users are asked to estimate their simulated speed within the environment. A longitudinal study of training outcomes using two of the simulators revealed systematic differences in task performance that matched differences measured using the perceptual task in a separate group of control subjects. A separate analysis of two standard presence questionnaires revealed that they were able to predict learning outcomes on a per individual basis, but that they were insensitive to the differences between the two simulators. The paper concludes by explaining how behavioral measures of the type proposed here can complement questionnaire-based studies, helping to motivate design aspects of new simulators, prompting changes to existing systems, and constraining training scenarios to maximize their efficacy.nonotspecifiedhttp://www.cyberneum.de/published18Predicting the Efficacy of Simulator-based Training Using a Perceptual Judgment Task Versus Questionnaire-based Measures of Presence1501715422WallravenD20133CWallravenLDopjans2013-03-00524254–258NeuroReportHumans are experts for face processing - this expertise develops over the course of several years, given visual input about faces from infancy. Recent studies have shown that individuals can also recognize faces haptically, albeit at lower performance than visually. Given that blind individuals are extensively trained on haptic processing, one may expect them to perform better at recognizing faces from touch than sighted individuals. Here, we tested this hypothesis using matched groups of sighted, congenitally blind, and acquired-blind individuals. Surprisingly, we found little evidence for a performance benefit for blind participants compared with sighted controls. Moreover, the congenitally blind group performed significantly worse than both the sighted and the acquired-blind group. Our results are consistent with the hypothesis that visual expertise may be necessary for haptic face recognition; hence, even extensive haptic training cannot easily account for deficits in visual processing.nonotspecifiedhttp://www.cyberneum.de/published-254Visual experience is necessary for efficient haptic face recognition1501715422VenrooijMAvvB20123JVenrooijMMulderDAAbbinkMMvan PaassenFCTvan der HelmHHBülthoff2013-02-00143129142IEEE Transactions on Systems, Man, and Cybernetics, Part B: CyberneticsWhen performing a manual control task, vehicle accelerations can cause involuntary limb motions, which can result in unintentional control inputs. This phenomenon is called biodynamic feedthrough (BDFT). In the past decades, many studies into BDFT have been performed, but its fundamentals are still only poorly understood. What has become clear, though, is that BDFT is a highly complex process, and its occurrence is influenced by many different factors. A particularly challenging topic in BDFT research is the role of the human operator, which is not only a very complex but also a highly adaptive system. In literature, two different ways of measuring and analyzing BDFT are reported. One considers the transfer of accelerations to involuntary forces applied to the control device (CD); the other considers the transfer of accelerations to involuntary CD deflections or positions. The goal of this paper is to describe an approach to unify these two methods. It will be shown how the results of the two methods relate and how this knowledge may aid in understanding BDFT better as a whole. The approach presented is based on the notion that BDFT dynamics can be described by the combination of two transfer dynamics: 1) the transfer dynamics from body accelerations to involuntary forces and 2) the transfer dynamics from forces to CD deflections. The approach was validated using experimental results.nonotspecifiedhttp://www.cyberneum.de/published13A New View on Biodynamic Feedthrough Analysis: Unifying the Effects on Forces and Positions1501715422HuberleL20133EHuberleWLutzenberger2013-02-0067119–126NeuroImageObject recognition is a fundamental mechanism of visual processing and requires the extraction of shape information. Early visual areas have been linked to the analysis of local image features, while higher visual areas of the ventral visual pathway rather mediate the perception and recognition of global shapes. Investigations of the spatiotemporal characteristics of shape analysis in the human visual cortex by rapid event-related fMRI adaptation in combination with a region of interest analysis suggested a transient manner of contour integration and shape processing in early visual areas compared to sustained processing in higher visual areas. fMRI adaptation (or repetition suppression) paradigms offer the possibility to enhance the restricted spatial resolution of conventional fMRI by focusing on decreased responses for repeated stimulus presentation. However, improving our understanding of complex neuronal mechanisms in the human brain requires the investigation not only at high spatial but also temporal resolution. A limitation of fMRI adaptation can be found in its poor temporal resolution which EEG- and MEG-techniques can overcome, though at a lower spatial resolution.
The present study aimed to investigate temporal characteristics of shape processing in the human brain by adapting the principles of fMRI adaption in a MEG study. In parallel to an earlier fMRI study, the two stimuli of a trial were presented at varied interstimulus intervals. Additional analyses by means of a dipole analysis and co-registration of MEG and fMRI data were conducted. Adaptation was observed for the short as well as the longer interstimulus interval. Interestingly, the latency of the adaptation effects varied with the interstimulus interval. The findings support a late onset of adaption that possibly underlies global discrimination processes and recognition in higher areas of the ventral visual pathway. Further, the present results indicate a useful extension of adaptation paradigms and ‘region of interest’-analyses from fMRI to MEG at a high temporal resolution.nonotspecifiedhttp://www.cyberneum.de/published-119Temporal properties of shape processing by event-related MEG adaptation1501715422ProffittL20112DRProffittSALinkenaugerMIT PressCambridge, MA, USA2013-02-00171198Action science: foundations of an emerging disciplineThis chapter describes empirical evidence for an approach aimed at examining visual perception. It proposes that visual perception is comprehended by the perceiver’s physical and biological characteristics in an effort to promote appropriate actions in the environment. Investigations also reveal that visual experience associates the visually perceived environment with continually changing purposes and the processes through which these purposes are achieved. The findings reveal that people adopt different skills and improve related expertise to perform specific tasks and achieve specific purposes. People also transform respective physical and biological characteristics to achieve certain objectives and associate perceptions with relevant physical and biological characteristics to perform specific actions.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/Proffitt-LinkenaugerZiFChapterColorPicsEmbedded.pdfpublished27Perception viewed as a phenotypic expression1501715422Streuber2013_215SStreuber2013-02-00nonotspecifiedpublishedThe Influence of Different Sources of Visual Information on Joint Action Performance1501715422NieuwenhuizenvSMB20123FMNieuwenhuizenMMvan PaassenOStroosmaMMulderHHBülthoff2013-01-0011123Journal of Modeling, Simulation, Identification, and Controlactuators, lower bandwidth, and higher motion noise. The influence of these characteristics on pilot perception and control behavior is unknown, and needs to be investigated. A possible approach to this would be to simulate a platform with limited capabilities with a high-end platform, and then remove the platform limitations one by one. The effects of these platform limitations on pilot behavior can then be investigated in isolation. In this paper, a model of a low-cost simulator was validated for simulation on a high-performance simulator. A dynamic model of the MPI Stewart platform was analyzed and compared with measurements of the baseline simulator response. Measurements for validation of the implementation of the model on the SIMONA Research Simulator showed that the dynamics of the MPI Stewart platform could be represented well in terms of dynamic range, timenonotspecifiedhttp://www.cyberneum.de/published22Cross-platform Validation for a Model of a Low-cost Stewart Platform1501715422ZhaoH20133MZhaoWGHayward2013-01-001:1513118Journal of VisionWhile separation of face identity and expression processing is favored by many face perception models, how the visual system analyzes identity and other face properties remains elusive. Here we investigated whether identity analysis is independent of or influenced by automatic processing of face gender and race. Participants searched for a target face among distractor faces whose gender or race was either the same as or different from the target face. Visual search was faster and more accurate when target and distractor faces differed in gender or race property than when not. The effect persisted for identification of both familiar and novel faces, and cannot be attributed to the low-level physical properties of stimuli or the earlier extraction of face gender/race information before identification. Together with complementary findings showing effects of identity analysis on gender and race categorization, these results indicate that invariant face properties are processed in an integrative way: visual analysis of one property involves, and is therefore affected by, automatic processing of the others. Implications for current theoretical models of face perception are discussed.nonotspecifiedhttp://www.cyberneum.de/published17Integrative processing of invariant aspects of faces: Effect of gender and race processing on identity analysis1501715422delaRosaGBC20123Sde la RosaMAGieseHHBülthoffCCurio2013-01-001:2313115Journal of VisionProbing emotional facial expression recognition with the adaptation paradigm is one way to investigate the processes underlying emotional face recognition. Previous research suggests that these processes are tuned to dynamic facial information (facial movement). Here we examined the tuning of processes involved in the recognition of emotional facial expressions to different sources of facial movement information. Specifically we investigated the effect of the availability of rigid head movement and intrinsic facial movements (e.g., movement of facial features) on the size of the emotional facial expression adaptation effect. Using a three-dimensional (3D) morphable model that allowed the manipulation of the availability of each of the two factors (intrinsic facial movement, head movement) individually, we examined emotional facial expression adaptation with happy and disgusted faces. Our results show that intrinsic facial movement is necessary for the emergence of an emotional facial expression adaptation effect with dynamic adaptors. The presence of rigid head motion modulates the emotional facial expression adaptation effect only in the presence of intrinsic facial motion. In a second experiment we show these adaptation effects are difficult to explain by merely the perceived intensity and clarity (uniqueness) of the adaptor expressions. Together these results suggest that processes encoding facial expressions are differently tuned to different sources of facial movements.nonotspecifiedhttp://www.cyberneum.de/published14The contribution of different cues of facial movement to the emotional facial expression adaptation aftereffect1501715422KrimmelKBBMDBR20133MKrimmelSKlubaMBreidtMBacherSMüller-HagedornKDietzHHBülthoffsReinert2013-01-00124313–316Journal of Craniofacial SurgeryChildren with cleft lip or cleft lip and alveolus represent a minor group in the cleft population. The aim of this study was to analyze the faces of these children. In a prospective, cross-sectional study, 344 healthy children and 30 children with cleft lip or cleft lip and alveolus were scanned three-dimensionally at the age of 0 to 6 years. Twenty-one standard anthropometric landmarks were identified, and the images were superimposed. Growth curves for normal facial development were calculated. The facial morphology of cleft children was compared with that of unaffected children.
Facial morphology and growth in the transverse direction of the examined patients appeared broadened in all levels. Especially the nasal landmarks indicated a widening of the nose. The landmarks ac l, sbal l, sbal r, c l, sn l, and ls l differed significantly from unaffected children. In the sagittal and vertical dimensions, there was no significant difference compared with unaffected children.
Our study demonstrates that surgical and orthodontic treatment can restore the vertical and sagittal dimensions of the face in children with cleft lip with and without alveolar clefts; however, the transverse dimension—especially the nose—remains too broad.nonotspecifiedhttp://www.cyberneum.de/published-313Three-Dimensional Assessment of Facial Development in Children With Unilateral Cleft Lip With and Without Alveolar Cleft1501715422BiegCBB20137H-JBiegLLChuangJ-PBrescianiHHBülthoffLinz, Austria2013-01-0023rd Oculomotor Meetingnonotspecifiedhttp://www.cyberneum.de/published0Asymmetric saccade initiation at smooth pursuit onset1501715422Soyka2013_215FSoyka2013-01-00nonotspecifiedpublishedA Cybernetic Approach to Self-Motion Perception1501715422Soyka20131FSoykaLogos VerlagBerlin, Germany2013-00-00Self-motion describes the motion of our body through the environment and is an essential part of our everyday life. The aim of this thesis is to improve our understanding of how humans perceive self-motion, mainly focusing on the role of the vestibular system. Following a cybernetic approach, this is achieved by systematically gathering psychophysical data and then describing it based on mathematical models of the vestibular sensors. Three studies were performed investigating perceptual thresholds for translational and rotational motions and reaction times to self-motion stimuli. Based on these studies, a model is introduced which is able to describe thresholds for arbitrary motion stimuli varying in duration and acceleration profile shape. This constitutes a significant addition to the existing literature since previous models only took into account the effect of stimulus duration, neglecting the actual time course of the acceleration profile. In the first and second study model parameters were identified based on measurements of direction discrimination thresholds for translational and rotational motions. These models were used in the third study to successfully predict differences in reaction times between varying motion stimuli proving the validity of the modeling approach. This work can allow for optimizing motion simulator control algorithms based on self-motion perception models and developing perception based diagnostics for patients suffering from vestibular disorders.Tübingen, Univ., Diss. 2013nonotspecifiedhttp://www.cyberneum.de/published96A Cybernetic Approach to Self-Motion Perception1501715422SteinickeVCL20131FSteinickeYVisellJCamposALécuyerSpringerNew York, NY, USA2013-00-00nonotspecifiedhttp://www.cyberneum.de/published402Human walking in virtual environments: perception, technology, and applications15017188241501715422Streuber20131SStreuberLogos VerlagBerlin, Germany2013-00-00Humans are social beings and they often act jointly together with other humans (joint actions) rather than alone. Prominent theories of joint action agree on visual information being critical for successful joint action coordination but are vague about the exact source of visual information being used during a joint action. Knowing which sources of visual information are used, however, is important for a more detailed characterization of the functioning of action coordination in joint actions.
The current Ph.D. research examines the importance of different sources of visual information on joint action coordination under realistic settings. In three studies I examined the influence of different sources of visual information (Study 1), the functional role of different sources of visual information (Study 2), and the effect of social context on the use of visual information (Study 3) in a table tennis game. The results of these studies revealed that (1) visual anticipation of the interaction partner and the interaction object is critical in natural joint actions, (2) different sources of visual information are critical at different temporal phases during the joint action, and (3) the social context modulates the importance of different sources of visual information. In sum, this work provides important and new empirical evidence about the importance of different sources of visual information in close-to-natural joint actions.Tübingen, Univ., Diss., 2013nonotspecifiedhttp://www.cyberneum.de/published114The Influence of Different Sources of Visual Information on Joint Action Performance1501715422RiedelFRBS20127MRiedelAFranchiPRobuffo GiordanoHHBülthoffHISonJeju Island, South Korea2013-00-0022723812th International Conference on Intelligent Autonomous Systems (IAS-12)In this paper we propose and experimentally validate
a bilateral teleoperation framework where a group of
UAVs are controlled over an unreliable network with typical
intercontinental time delays and packet losses. This setting is meant to represent a realistic and challenging situation for the stability the bilateral closed-loop system. In order to increase human telepresence, the system provides the operator with both a video stream coming from the onboard cameras mounted on the UAVs, and with a suitable haptic cue, generated by a forcefeedback
device, informative of the UAV tracking performance
and presence of impediments on the remote site.
In addition to the theoretical background, we describe the
hardware and software implementation of this intercontinental teleoperation: this is composed of a semi-autonomous group of multiple quadrotor UAVs, a 3-DOF haptic interface, and a network connection based on a VPN tunnel between Germany and South Korea. The whole software framework is based upon the Robotic Operating System (ROS) communication standard.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/IAS-2012-Riedel2.pdfpublished11Experiments on Intercontinental Haptic Control of Multiple UAVs1501715422SongNKHS20137EUSongMNiitsumaTKubotaHHashimotoHISonGwangju, South Korea2013-00-00911041st International Conference on Robot Intelligence Technology and Applications (RiTA 2012)This paper proposes an intuitive teleoperation scheme by using human gesture in conjunction with multimodal human-robot interface. Further, in order to deal with the complication of dynamic daily environment, the authors apply haptic point cloud rendering and the virtual collaboration to the system. all these functions are achieved by a portable hardware that is proposed by authors newly, which is called “the mobile iSpace”. First, a surrounding environment of a teleoperated robot is captured and reconstructed as the 3D point cloud using a depth camera. Virtual world is then generated from the 3D point cloud, which a virtual teleoperated robot model is placed in. Operators use their own whole-body gesture to teleoperate the humanoid robot. The Gesture is captured in real time using the depth camera that was placed on operator side. The operator recieves both the visual and the vibrotactile feedback at the same time by using a head mounted display and a vibrotactile glove. All these system components, the human operator, the teleoperated robot and the feedback devices, are connected with the Internet-based virtual collaboration system for a flexible accessibility. This paper showcases the effectiveness of the proposed scheme with experiment that were done to show how the operators can access the remotely placed robot in anytime and place.nonotspecifiedhttp://www.cyberneum.de/published13Multimodal Human-Robot Interface with Gesture-Based Virtual Collaboration1501715422Bulthoff2013_87HHBülthoffGöttingen, Germany2013-00-007183127. Versammlung der Gesellschaft Deutscher Naturforscher und Ärzte e. V. 2012Ein alltägliches Szenario: Stau auf den Autobahnen, die Städte sind verstopft, Züge und Busse sind hoffnungslos überfüllt. Der Pendlerverkehr ist längst an seine Grenzen gestoßen und nur bedingt kann der Ausbau des Verkehrsnetzes Abhilfe schaffen. Doch wie sehen die Alternativen aus? Ein Traum: Der Individualverkehr hebt ab in die dritte Dimension. Diese Vision verfolgt Prof. Heinrich Bülthoff mit dem EU-Projekt „myCopter“. Ziel ist nicht, ein fliegendes Auto zu bauen, sondern die technischen und gesellschaftlichen Bedingungen zu klären, unter denen sie zu einem akzeptierten und brauchbaren Verkehrsmittel werden.nonotspecifiedhttp://www.cyberneum.de/published12Und wenn wir einfach zur Arbeit fliegen? Welche Bedingungen sind nötig, um fliegende Autos Realität werden zu lassen?1501715422FrissenCSE20132IFrissenJLCamposMSreenivasaMOErnstSpringerNew York, NY, USA2013-00-00113144Human Walking in Virtual Environments: Perception, Technology, and ApplicationsThe CyberWalk treadmill is the first truly omnidirectional treadmill of its size that allows for near natural walking through arbitrarily large Virtual Environments. The platform represents advances in treadmill and virtual reality technology and engineering, but it is also a major step towards having a single setup that allows the study of human locomotion and its many facets. This chapter focuses on the human behavioral research that was conducted to understand human locomotion from the perspective of specifying design criteria for the CyberWalk. The first part of this chapter describes research on the biomechanics of human walking, in particular, the nature of natural unconstrained walking and the effects of treadmill walking on characteristics of gait. The second part of this chapter describes the multisensory nature of walking, with a focus on the integration of vestibular and proprioceptive information during walking. The third part of this chapter describes research on large-scale human navigation and identifies possible causes for the human tendency to veer from a straight path, and even walk in circles when no external references are made available. The chapter concludes with a summary description of the features of the CyberWalk platform that were informed by this collection of research findings and briefly highlights the current and future scientific potential for this platform.nonotspecifiedhttp://www.cyberneum.de/published31Enabling Unconstrained Omnidirectional Walking Through Virtual Environments: An Overview of the CyberWalk Project15017188241501715422Ruddle20132RARuddleSpringerNew York, NY, USA2013-00-0099112Human Walking in Virtual Environments: Perception, Technology, and ApplicationsPhysical locomotion provides internal (body-based) sensory information about the translational and rotational components of movement. This chapter starts by summarizing the characteristics of model-, small- and large-scale VE applications, and attributes of ecological validity that are important for the application of navigation research. The type of navigation participants performed, the scale and spatial extent of the environment, and the richness of the visual scene are used to provide a framework for a review of research into the effect of body-based information on navigation. The review resolves contradictions between previous studies’ findings, identifies types of navigation interface that are suited to different applications, and highlights areas in which further research is needed. Applications that take place in small-scale environments, where maneuvering is the most demanding aspect of navigation, will benefit from full-walking interfaces. However, collision detection may not be needed because users avoid obstacles even when they are below eye-level. Applications that involve large-scale spaces (e.g., buildings or cities) just need to provide the translational component of body-based information, because it is only in unusual scenarios that the rotational component of body-based information produces any significant benefit. This opens up the opportunity of combining linear treadmill and walking-in-place interfaces with projection displays that provide a wide field of view.nonotspecifiedhttp://www.cyberneum.de/published13The Effect of Translational and Rotational Body-Based Information on Navigation1501715422Bulthoff2012_1210HHBülthoffFranchiR20127AFranchiPRobuffo GiordanoMaui, HI, USA2012-12-005310531751th IEEE Conference on Decision and Control (CDC 2012)In this paper we analyze the relationship between
scalability, minimality and rigidity, and its application to
cooperative control. As a case study, we address the problem
of multi-agent formation control by proposing a distributed
control strategy that stabilizes a formation described with
bearing (direction) constraints, and that only requires bearing measurements and parallel rigidity of the interaction graph. We also consider the possibility of having different graphs modeling the interaction network in order to explicitly take into account the conceptual difference between sensing, communication, control, and parameters stored in the network. We then show how the information can be ‘moved’ from a graph to another making use of decentralized estimation, provided the parallel
rigidity property. Finally we present simulative examples in
order to show the validity of the theoretical analysis in some illustrative cases.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/2012i-FraRob-preprint.pdfpublished7Decentralized Control of Parallel Rigid Formations with Direction Constraints and Bearing Measurements1501715422SongNKHS20167YESongMNiitsumaTKubotaHHashimotoHISonKosice, Slovakia2012-12-00627631IEEE 3rd International Conference on Cognitive Infocommunications (CogInfoCom 2012)This paper proposes an intuitive teleoperation scheme by using human gesture in conjunction with multimodal human-robot interface. Further, in order to deal with the complication of dynamic daily environment, the authors apply haptic point cloud rendering and the virtual collaboration to the system. all these functions are achieved by a portable hardware that is proposed by authors newly, which is called “the mobile iSpace”. First, a surrounding environment of a teleoperated robot is captured and reconstructed as the 3D point cloud using a depth camera. Virtual world is then generated from the 3D point cloud, which a virtual teleoperated robot model is placed in. Operators use their own whole-body gesture to teleoperate the humanoid robot. The Gesture is captured in real time using the depth camera that was placed on operator side. The operator recieves both the visual and the vibrotactile feedback at the same time by using a head mounted display and a vibrotactile glove. All these system components, the human operator, the teleoperated robot and the feedback devices, are connected with the Internet-based virtual collaboration system for a flexible accessibility. This paper showcases the effectiveness of the proposed scheme with experiment that were done to show how the operators can access the remotely placed robot in anytime and place.nonotspecifiedhttp://www.cyberneum.de/published4Mobile multimodal human-robot interface for virtual collaboration1501715422NieuwenhuizenBM201210FMNieuwenhuizenHHBülthoffMMulderBulthoff2012_1110HHBülthoffCurio2012_210CCurioBulthoff2012_1010HHBülthoffChuang201210LChuangSongNKHS20127YESongMNiitsumaTKubotaHHashimotoHISonDaejeon, South Korea2012-11-0018229th International Conference on Ubiquitous Robots and Ambient Intelligence (URAI 2012)We present a intuitive teleoperation scheme by using human gesture and multimodal multi-user human-robot interface. Further, in order to deal with the dynamic daily environment, we apply haptic point cloud rendering and virtual collaboration and all these functions are achieved by portable hardwares which is called “mobile iSpace”. First, a surrounding environment of a teleoperated robot is captured and reconstructed as the 3D point cloud using a depth camera. Virtual world is then generated from the 3D point cloud, and a virtual teleoperated robot model is placed in there. An user uses their own whole body gesture to teleoperate the humanoid type robot. The gesture is captured by the depth camera placed in user-side in real time. And the user has the visual and vibrotactile feedback at the same time by using a head mounted display and a vibrotactile glove. All these system components e.g. the human user, the teleoperated robot and the feedback devices are connected with the Internet-based virtual collaboration system to support a flexible accessibility. So eventually, this makes possible that users can access the remote placed robot whenever and wherever they want.nonotspecifiedhttp://www.cyberneum.de/published4Multimodal multi-user human-robot interface for virtual collaboration1501715422LacheleFBR20127JLächeleAFranchiHHBülthoffPRobuffo GiordanoTsukuba, Japan2012-11-003753873rd International Conference on Simulation, Modeling, and Programming for Autonomous Robots (SIMPAR 2012)In this paper we present a novel simulation environment called SwarmSimX with the ability to simulate dozens of robots in a realistic 3D environment. The software architecture of SwarmSimX allows new robots, sensors, and other libraries to be loaded at runtime, extending the functionality of the simulation environment significantly. In addition, SwarmSimX allows an easy exchange of the underlying libraries used for the visual and physical simulation to incorporate different libraries (e.g., improved or future versions). A major feature is also the possibility to perform the whole simulation in real-time allowing for human-in-the-loop or hardware-in-the-loop scenarios. SwarmSimX has been already employed in several works presenting haptic shared control of multiple mobile robots (e.g., quadrotor UAVs). Additionally, we present here two validation tests showing the physical fidelity and the real-time performance of SwarmSimX. For the tests we used NVIDIA® PhysX® and Ogre3D as physics and rendering libraries, respectively.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/2012m-LaeFranchiBueRob-preprint.pdfpublished12SwarmSimX: Real-time Simulation Environment for Multi-robot Systems1501715422EsinsSKWB2012_27JEsinsJSchultzBRKimCWallravenIBülthoffSchramberg, Germany2012-11-003813th Conference of the Junior Neuroscientists of Tübingen (NeNA 2012): Science and Education as Social Transforming AgentsCongenital prosopagnosia, an innate impairment in recognizing faces, as well as the otherrace-effect, the disadvantage in recognizing faces of foreign races, both influence face recognition abilities. Here we compared both phenomena by testing three groups: German congenital
prosopagnosics (cPs), unimpaired German and unimpaired South Korean participants (n=23 per group), on three tests with Caucasian faces. First we ran the Cambridge Face Memory
Test (Duchaine & Nakayama, 2006 Neuropsychologia 44 576-585). Participants had to recognize Caucasian target faces in a 3AFC task. German controls performed better than
Koreans (p=0.009) who performed better than prosopagnosics (p=0.0001). Variation of the individual performances was larger for cPs than for Koreans (p = 0.028). In the second experiment, participants rated the similarity of Caucasian faces (in-house 3D face-database) which differed parametrically in features or second order relations (configuration). We found differences between sensitivities to change type (featural or configural, p=0) and between
groups (p=0.005) and an interaction between both factors (p = 0.019). During the third experiment, participants had to learn exemplars of artificial objects (greebles), natural objects (shells), and faces and recognize them among distractors. The results showed an interaction (p = 0.005) between stimulus type and participant group: cPs where better for non-face stimuli and worse for face stimuli than the other groups. Our results suggest that congenital
prosopagnosia and the other-race-effect affect face perception in different ways. The broad range in performance for the cPs directs the focus of our future research towards looking for different forms of congenital prosopagnosia.nonotspecifiedhttp://www.cyberneum.de/published-38Comparing the other race effect and congenital prosopagnosia using a three-experiment test battery1501715422NestiBPB20127ANestiKBeykirchPPrettoHHBülthoffSchramberg, Germany2012-11-002713th Conference of the Junior Neuroscientists of Tübingen (NeNA 2012): Science and Education as Social Transforming AgentsSensory information processes leading to human self-motion perception have been modelled in the past in terms of visual and inertial stimulations and their interactions. The models, validated through many psychophysical experiments, rely on the assumption that our sensitivity
to supra-threshold self-motion is not affected by motion intensity. In other words, the relationship between motion stimulus intensity and human sensitivity to motion is assumed to be linear. However, recent studies have shown that this relationship is non-linear, in particular at higher motion intensity. Therefore, the implementation of nonlinearities in the computational models of human motion perception would increase their accuracy over a wider range of motion stimulus intensity. Here we test human sensitivity for sinusoidal yaw rotation in darkness at frequencies of 0.5 Hz and 1 Hz and velocity amplitudes ranging between 0 and 90 deg/s. In a two interval force choice experimental paradigm, subjects undergo two consecutive rotations in the same direction for each trial. One of these movements is repeated unchanged in every trial, while the other systematically varies in amplitude. Subjects are asked to report after each trial which one of the two movements was stronger. An adaptive staircase adjusts the motion for every trial to identify the smallest detectable change in stimulus intensity (differential threshold). Results show a power law relationship between
differential thresholds and stimulus intensity, meaning that sensitivity decreases as motion becomes stronger. No frequency effect is observed. These findings are of particular interest for the field of vehicle motion simulation, where knowledge about self-motion perception is widely exploited to overcome the physical limitations of motion-based simulators. Furthermore, the identification of perceptual nonlinearities in multisensory stimulation will guide future work into understanding the neural mechanisms responsible for self-motion perception.nonotspecifiedhttp://www.cyberneum.de/published-27Human sensitivity to different motion intensities1501715422Franchi2012_410AFranchiSoyka201210FSoykaVolkovaMB201210EPVolkovaBJMohlerHHBülthoffDwarakanathPHE201210ADwarakanathCPariseJHartcher-O'BrienMErnstNieuwenhuizenCB201210FNieuwenhuizenLChuangHHBülthoffStreuber201210SStreuberGianiN2012_210AGianiUNoppeneyBulthoff2012_1510IBülthoffNieuwenhuizenB201210FNieuwenhuizenHHBülthoffNieuwenhuizen2012_210FNieuwenhuizenRiedelFBR201210MRiedelAFranchiHHBülthoffPRobuffo GiordanoMasoneFBR2012_210CMasoneAFranchiHHBülthoffPRobuffo GiordanoButlerDNWBRF201210JSButlerPDesanctisHNolanRWhelanHHBülthoffOReillyJFoxeRoheN2012_27TRoheUNoppeneyNew Orleans, LA, USA2012-10-1542nd Annual Meeting of the Society for Neuroscience (Neuroscience 2012)Previous research has demonstrated that human observers locate audiovisual signals in space by averaging auditory (A) and visual (V) spatial signals according to their relative sensory reliabilities (=inverse of variance) (Ernst & Banks, 2002; Alais & Burr, 2004). This form of audiovisual integration is optimal in that it provides the most reliable percept.Yet, the neural systems mediating integration of spatial inputs remain unclear. Multisensory integration of spatial signals has previously been related to higher order association areas such as intraparietal sulcus (IPS) as well as the planum temporale (PT; Bonath et al., 2007). In the current fMRI study, we investigated whether and how early sensory (auditory cortex (A1), PT; visual regions V1-V3) and higher association (IPS) areas represent A and V spatial information. Subjects were presented with synchronous audiovisual signals, at spatially congruent or discrepant locations along the azimuth and at two levels of sensory reliability. Hence, the experimental design factorially manipulated: (1) V location, (2) A location, (3) V reliability. Subjects’ task was to localize the A signal. At the behavioral level, the perceived location of the A input was shifted towards the location of the V input depending on the relative A and V reliabilities. Likewise, at the neural level, the spatial location decoded with linear support vector machines from fMRI signals in brain areas along the A and V processing hierarchies was determined by the relative sensory reliabilities. The spatial location decoded from A1/PT was determined primarily by A spatial information with a stronger influence from V spatial information when the V reliability was high. Conversely, the spatial location decoded from visual areas (V1, V2, V3) and IPS was determined primarily by V spatial information with a stronger A influence when the V information was less reliable. In conclusion, our results suggest that the brain represents audiovisual spatial location in qualitative agreement with reliability-weighted multisensory integration at multiple levels of the cortical processing hierarchy.nonotspecifiedhttp://www.cyberneum.de/published0Neural audiovisual representations of space in sensory and higher multisensory cortices15017154221501718826Bulthoff2012_810HHBülthoffBulthoff2012_910HHBülthoffCurio201210CCurioBulthoff2012_710HHBülthoffLinkenaugerLRP20123SLinkenaugerMDLernerVCRamenzoniDProffitt2012-10-0055352–362Autism ResearchIndividuals with autism spectrum disorders (ASDs) have known impairments in social and motor skills. Identifying putative underlying mechanisms of these impairments could lead to improved understanding of the etiology of core social/communicative deficits in ASDs, and identification of novel intervention targets. The ability to perceptually integrate one's physical capacities with one's environment (affordance perception) may be such a mechanism. This ability has been theorized to be impaired in ASDs, but this question has never been directly tested. Crucially, affordance perception has shown to be amenable to learning; thus, if it is implicated in deficits in ASDs, it may be a valuable unexplored intervention target. The present study compared affordance perception in adolescents and adults with ASDs to typically developing (TD) controls. Two groups of individuals (adolescents and adults) with ASDs and age-matched TD controls completed well-established action capability estimation tasks (reachability, graspability, and aperture passability). Their caregivers completed a measure of their lifetime social/communicative deficits. Compared with controls, individuals with ASDs showed unprecedented gross impairments in relating information about their bodies' action capabilities to visual information specifying the environment. The magnitude of these deficits strongly predicted the magnitude of social/communicative impairments in individuals with ASDs. Thus, social/communicative impairments in ASDs may derive, at least in part, from deficits in basic perceptual–motor processes (e.g. action capability estimation). Such deficits may impair the ability to maintain and calibrate the relationship between oneself and one's social and physical environments, and present fruitful, novel, and unexplored target for intervention.nonotspecifiedhttp://www.cyberneum.de/published-352A Perceptual–Motor Deficit Predicts Social and Communicative Impairments in Individuals With Autism Spectrum Disorders1501715422YuilleB20123ALYuilleHHBülthoff2012-10-00441091773617737Proceedings of the National Academy of Sciences of the United States of AmericaBabies are faced at birth with a buzzing blooming confusion of visual stimuli (1). The set of all possible images is truly enormous (2), and simple calculations suggest that only a small fraction of all possible images have ever been seen over the entire history and prehistory of mankind. Moreover, the world consists of an estimated number of 30,000 objects (3), which occur in more than 1,000 different types of scenes. How can an infant start making sense of the visual world?
Detailed models of how infants learn to understand images and the balance between nature and nurture are currently lacking. Studies suggest that visual abilities develop in a stereotyped order (4). In particular, infants appear to be able to perceive motion and detect faces at an early stage of development. They can probably exploit the regularities that motion tends to be smooth in space and time, which also enables them to track image patches. Vision researchers have also demonstrated that many vertebrates and insects rely heavily on motion perception for surviving in this complex visual world, e.g., for camouflage breaking or figure ground separation (5, 6), and there are computational models that relate to neural circuitry (7).nonotspecifiedhttp://www.cyberneum.de/published1Action as an innate bias for visual learning1501715422FranchiSSBR20123AFranchiCSecchiHISonHHBülthoffPRobuffo Giordano2012-10-0052810191033IEEE Transaction on RoboticsIn this paper, a novel decentralized control strategy for bilaterally teleoperating heterogeneous groups of mobile robots from different domains (aerial, ground, marine, and underwater) is proposed. By using a decentralized control architecture, the group of robots, which is treated as the slave side, is made able to navigate in a cluttered environment while avoiding obstacles, interrobot collisions, and following the human motion commands. Simultaneously, the human operator acting on the master side is provided with a suitable force feedback informative of the group response and of the interaction with the surrounding environment. Using passivity-based techniques, we allow the behavior of the group to be as flexible as possible with arbitrary split and join events (e.g., due to interrobot visibility/packet losses or specific task requirements) while guaranteeing the stability of the system. We provide a rigorous analysis of the system stability and steady-state characteristics and validate performance through human/hardware-in-the-loop simulations by considering a heterogeneous fleet of unmanned aerial vehicles (UAVs) and unmanned ground vehicles as a case study. Finally, we also provide an experimental validation with four quadrotor UAVs.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/2012e-FraSecSonBueRob.pdfpublished14Bilateral Teleoperation of Groups of Mobile Robots with Time-Varying Topology1501715422AlaimoPIBB20123SMCAlaimoLPolliniMInnocentiJPBrescianiHHBülthoff2012-10-00102628637Journal of Mechanics Engineering and AutomationThe sense of telepresence is known to be essential in teleoperation environments, where the operator is physically separated from the vehicle. Usually only a visual feedba
ck is provided, but it has been shown that by extending the visual interface with haptic feedback, that is complementing the visual information through the sense of touch, the teleoperat or has a better perception of
information from the remote environment and its constraints. This paper focuses on a novel concept of haptic cueing for an airborne obstacle avoidance task; the novel cueing
algorithm was designed to appear “natural” to the operator, and to improve the human-machine interface without directly acting on the actual aircraft commands. Two different haptic aiding concepts for obstacle avoidance support are presented: an existing and widely used system, belonging to what we called the Direct Haptic Aid (DHA) approach class, and a novel one based on the Indirect Haptic Aid (IHA) approach class. Tests with human operators show that a net improvement in terms of performance (i.e., the number of collisions) is provided by employing the IHA haptic cue as compared to both the DHA haptic cue and/or the visual cues only. The results clear ly show that the IHA philosophy is a valid alternative to the other commonly used approaches, which fall in the DHA category.nonotspecifiedhttp://www.cyberneum.de/published9Experimental Comparison of Direct and Indirect Haptic Aids in Support of Obstacle Avoidance for Remotely Piloted Vehicles1501715422PrettoBRB20123PPrettoJ-PBrescianiGRainerHHBülthoff2012-10-001112eLifeVisual speed is believed to be underestimated at low contrast, which has been proposed as an explanation of excessive driving speed in fog. Combining psychophysics measurements and driving simulation, we confirm that speed is underestimated when contrast is reduced uniformly for all objects of the visual scene independently of their distance from the viewer. However, we show that when contrast is reduced more for distant objects, as is the case in real fog, visual speed is actually overestimated, prompting drivers to decelerate. Using an artificial anti-fog—that is, fog characterized by better visibility for distant than for close objects, we demonstrate for the first time that perceived speed depends on the spatial distribution of contrast over the visual scene rather than the global level of contrast per se. Our results cast new light on how reduced visibility conditions affect perceived speed, providing important insight into the human visual system.nonotspecifiedhttp://www.cyberneum.de/published11Foggy perception slows us down1501715422FranchiMGRBR20123AFranchiCMasoneVGrabeMRyllHHBülthoffPRobuffo Giordano2012-10-00123115041525International Journal of Robotics ResearchIn this paper we address the problem of controlling the motion of a group of unmanned aerial vehicles (UAVs) bound to keep a formation defined in terms of only relative angles (i.e. a bearing formation). This problem can naturally arise within the context of several multi-robot applications such as, e.g. exploration, coverage, and surveillance. First, we introduce and thoroughly analyze the concept and properties of bearing formations, and provide a class of minimally linear sets of bearings sufficient to uniquely define such formations. We then propose a bearing-only formation controller requiring only bearing measurements, converging almost globally, and maintaining bounded inter-agent distances despite the lack of direct metric information.
The controller still leaves the possibility of imposing group motions tangent to the current bearing formation. These can be either autonomously chosen by the robots because of any additional task (e.g. exploration), or exploited by an assisting human co-operator. For this latter ‘human-in-the-loop’ case, we propose a multi-master/multi-slave bilateral shared control system providing the co-operator with some suitable force cues informative of the UAV performance. The proposed theoretical framework is extensively validated by means of simulations and experiments with quadrotor UAVs equipped with onboard cameras. Practical limitations, e.g. limited field-of-view, are also considered.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/2012q-FraMasGraRylBueRob-preprint.pdfpublished21Modeling and Control of UAV Bearing-Formations with Bilateral High-Level Steering1501715422ShinLBW20127AShinS-WLeeHHBülthoffCWallravenSeoul, South Korea2012-10-0022832288IEEE International Conference on Systems, Man, and Cybernetics (SMC 2012)A 3D morphable face model represents the complex shape and appearance structure of faces as a compact representation in a vector space. Such a model has proven extremely useful in various fields such as face recognition, facial expression synthesis, face animation, as well as in the perceptual and cognitive sciences. One of the most important steps in creating a 3D morphable model is to establish correspondence between all faces - a highly non-trivial process because of the complex topology of faces. In this paper, we propose to use implicit surfaces for this task, which enables a robust method for establishing dense 3D correspondences. This algorithm is used to build a morphable face model from a large database of Korean faces that were collected. We show that our model is in correspondence with the well-known MPI model so that our face space can be expanded from Asian to Caucasian faces. In addition, with the resulting control parameters of the model, we demonstrate realistic changes of high-level facial attributes.nonotspecifiedhttp://www.cyberneum.de/published5A Morphable 3D-Model of Korean Faces1501715422FranchiMR20127AFranchiCMasonePRobuffo GiordanoVilamoura, Portugal2012-10-0015202012 IEEE IROS Workshop on Robot Motion Planning: Online, Reactive, and in Real-timeIn this work we present a novel framework for the
systematic integration of high-level/mission schedulers, middlelevel/cognitive-enabled online-planners and low-level/reactive trajectory modifiers. The approach does not rely on a particular parametrization of the trajectory and assumes a basic environment representation. As an application, the online capabilities of the method can be used to let a mobile robot cooperate with a human taking the role of the middle-level planner. In that case
we also describe a rigorous way to bilaterally couple the human and the reactive planner in order to provide an immersive haptic feeling of the planner state. Hardware/Human in-the-loop simulations, with a quadrotor UAV used as robotic platform and a real haptic instrument, are provided as validating showcase of the presented theoretical framework.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/2012o-FraMasRob-preprint.pdfpublished5A Synergetic High-level/Reactive Planning Framework with Application to Human-Assisted Navigation1501715422SpicaFOBR20127RSpicaAFranchiGOrioloHHBülthoffPRobuffo GiordanoVilamoura, Portugal2012-10-0049854992IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2012)Abstract—For a quadrotor aircraft, we study the problem of
planning a trajectory that connects two arbitrary states while allowing the UAV to grasp a moving target at some intermediate time. To this end, two classes of canonical grasping maneuvers are defined and characterized. A planning strategy relying on differential flatness is then proposed to concatenate one or more grasping maneuvers by means of spline-based subtrajectories, with the additional objective of minimizing the total transfer time. The proposed planning algorithm is not restricted to pure
hovering-to-hovering motions and takes into account practical constraints, such as the finite duration of the grasping phase. The effectiveness of the proposed approach is shown by means of physically-based simulations.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/IROS-2012-Spica.pdfpublished7Aerial Grasping of a Moving Target with a Quadrotor UAV1501715422SonHBL20127HISonAHongHHBülthoffDLeeJeju, South Korea2012-10-001772177712th International Conference on Control, Automation and Systems (ICCAS 2012)There is, practically, imperfect communication network (e.g., time delay and packet loss/switching) in haptic interaction (or teleoperation) systems. It is well known that such imperfect communication degrades teleoperator's performance as well as stability. We hypothesis that as an imperfectness level in the communication network is increasing, the teleoperator's performance is decreasing monotonically. In this paper, we verified the hypothesis via a human-centered evaluation of the teleoperator's perceptual performance in terms of just noticeable difference (JND), point of subject equality (PSE), and perception time using two psychophysical experiments: experiment of packet separation time and experiment of packet loss. In the experiment of packet separation time, there were significant increases of JND and PSE as the packet separation time was increased. However, interestingly, there was no significant decrease of teleoperator's perceptual performance in the experiment of packet loss although the packet loss rate was increased until 75 %. The experimental results clearly shows that the packet separation time affects on the teleoperator's perceptual performance more than the packet loss rate.nonotspecifiedhttp://www.cyberneum.de/published5Effects of imperfect communication network on haptic teleoperator's performance1501715422HongCL20127AHongJHChoDYLeeJeje, South Korea2012-10-001762176712th International Conference on Control, Automation and Systems (ICCAS 2012)Telesurgery has come to the forefront because of many merits such as a small incision, less bleeding and a short period of hospitalization. By means of internet, telesurgery is practical even the master and the slave are not physically in the same place. Internet, however, causes communication constraints such as time-varying delay and packet loss which induce instability and performance degradations in teleoperation systems. In this paper, we consider teleoperation systems including bilateral communications with asynchronous packet loss and time-varying delay. We define teleoperation sytsems as polytopic linear differential inclusions (PLDIs) to cope with switchings between subsystems which are divided by the status of communication channels. A sufficient condition which guarantees asymptotic stability and H_\infty performance is derived for teleoperation systems modeled as PLDIs. Then, we propose a H_\infty control design method, using linear matrix inequalities (LMIs).nonotspecifiedhttp://www.cyberneum.de/published5H∞ Control of Bilateral Telesurgical Systems with Communication Constraints1501715422VenrooijMvAvMB20127JVenrooijMMulderMMvan PaassenDAAbbinkVCTvan der HelmMulderMHHBülthoffSeoul, South Korea2012-10-0021502155IEEE International Conference on Systems, Man, and Cybernetics (SMC 2012)Biodynamic feedthrough (BDFT) refers to a phenomenon where vehicle accelerations feed through the human body, causing involuntary limb motions, which may cause involuntary control inputs. Many studies have been devoted to mitigating BDFT effects. In the current paper, the effectiveness of a simple, cheap and widely-used hardware component is studied: the armrest. An experiment was conducted in which the BDFT dynamics were measured with and without armrest for different levels of neuromuscular admittance (i.e., different settings of the limb dynamics). The results show that the effect of the armrest on BDFT dynamics varies, both with frequency and neuromuscular admittance.nonotspecifiedhttp://www.cyberneum.de/published5How effective is an armrest in mitigating biodynamic feedthrough?1501715422DropPDVM2012_27FMDropDMPoolHJDamveldMMvan PaassenHHBülthoffMMulderSeoul, South Korea2012-10-0020082013IEEE International Conference on Systems, Man, and Cybernetics (SMC 2012)The human in manual control of a dynamical system can use both feedback and feedforward control strategies and will select a strategy based on performance and required effort. Literature has shown that feedforward control is used during tracking tasks in response to predictable targets. The influence of an external disturbance signal on the utilization of a feedforward control strategy has never been investigated, however. We hypothesized that the human will use a combined feedforward and feedback control strategy whenever the predictable target signal is sufficiently strong, and a predominantly feedback strategy whenever the random disturbance signal is dominant. From the data of a human-in-the-loop experiment we conclude that feedforward control is used in all the considered experimental conditions, including those where the disturbance signal is dominant and feedforward control does not deliver a marked performance advantage.nonotspecifiedhttp://www.cyberneum.de/published5Identification of the Transition from Compensatory to Feedforward Behavior in Manual Control1501715422MasoneFBR20127CMasoneAFranchiHHBülthoffRRobuffo GiordanoVilamoura, Portugal2012-10-0026412648IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2012)This work extends the framework of bilateral shared control of mobile robots with the aim of increasing the robot autonomy and decreasing the operator commitment. We
consider persistent autonomous behaviors where a cyclic motion must be executed by the robot. The human operator is in charge of modifying online some geometric properties of the desired path. This is then autonomously processed by the robot in order to produce an actual path guaranteeing: i) tracking feasibility, ii) collision avoidance with obstacles, iii) closeness to the desired path set by the human operator, and iv) proximity to some points of interest. A force feedback is implemented to inform
the human operator of the global deformation of the path
rather than using the classical mismatch between desired and
executed motion commands. Physically-based simulations, with
human/hardware-in-the-loop and a quadrotor UAV as robotic
platform, demonstrate the feasibility of the method.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/IROS-2012-Masone.pdfpublished7Interactive Planning of Persistent Trajectories for Human-Assisted Navigation of Mobile Robots1501715422KohlerHMSH20127RKöhlerMHirschBMohlerBSchölkopfSHarmelingFirenze, Italy2012-10-00274012th European Conference on Computer VisionMotion blur due to camera shake is one of the predominant sources of degradation in handheld photography. Single image blind deconvolution (BD) or motion deblurring aims at restoring a sharp latent image from the blurred recorded picture without knowing the camera motion that took place during the exposure. BD is a long-standing problem, but has attracted much attention recently, cumulating in several algorithms able to restore photos degraded by real camera motion in high quality. In this paper, we present a benchmark dataset for motion deblurring that allows quantitative performance evaluation and comparison of recent approaches featuring non-uniform blur models. To this end, we record and analyse real camera motion, which is played back on a robot platform such that we can record a sequence of sharp images sampling the six dimensional camera motion trajectory. The goal of deblurring is to recover one of these sharp images, and our dataset contains all information to assess how closely various algorithms approximate that goal. In a comprehensive comparison, we evaluate state-of-the-art single image BD algorithms incorporating uniform and non-uniform blur models.nonotspecifiedhttp://www.cyberneum.de/published13Recording and Playback of Camera Shake: Benchmarking Blind Deconvolution with a Real-World Database15017154221501715420GrabeBR20127VGrabeHHBülthoffPRobuffo GiordanoVilamoura, Portugal2012-10-0021532159IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2012)Robotic vision has become an important field of research for micro aerial vehicles in the recent years. While many approaches for autonomous visual control of such vehicles rely on powerful ground stations, the increasing availability of small and light hardware allows for the design of more independent systems. In this context, we present a robust algorithm able to recover the UAV ego-motion using a monocular camera and on-board hardware. Our method exploits the continuous homography constraint so as to discriminate among the observed feature points in order to classify those belonging to the dominant plane in the scene. Extensive experiments on a real quadrotor UAV demonstrate that the estimation of the scaled linear velocity in a cluttered environment improved by a factor of 25% compared to previous approaches.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/IROS-2012-Grabe.pdfpublished6Robust Optical-Flow Based Self-Motion Estimation for a Quadrotor UAV1501715422CognettiSFO20127MCognettiPStegagnoAFranchiGOrioloEspoo, Finland2012-10-0013182nd IFAC Workshop on Multivehicle Systems (MVS 2012)We present a method for reconstructing the relative poses among the components of a multi-UAV system using anonymous (i.e., without identity information) robot-to-robot measurements. We consider two cases: bearing-only and bearing+distance measurements. While bearing can be rather directly extracted from a camera image, visual reconstruction of distances is more elaborate and typically associated with a larger noise. Nevertheless, our experiments show that use of such metric information improves significantly the quality of the localization.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/2012l-CogSteFraOri-preprint.pdfpublished5Two Measurement Scenarios for Anonymous Mutual Localization in Multi-UAV Systems1501715422MohlerdB20122BJMohlerMDi LucaHHBülthoffAmerican Psychological AssociationWashington, DC, USA2012-10-008197Handbook of Spatial CognitionHow do we know where environmental objects are located with respect to our body? How are we are able to navigate, manipulate, and interact with the environment? In this chapter, we describe how capturing sensory signals from the environment and performing internal computations achieve such goals. The first step, called early or low-level processing, is based on the functioning of feature detectors that respond selectively to elementary patterns of stimulation. Separate organs capture sensory signals and then process them separately in what we normally refer to as senses: smell, taste, touch, audition, and vision. In the first section of this chapter, we present the sense modalities that provide sensory information for the perception of spatial properties such as distance, direction, and extent. Although it is hard to distinguish where early processing ends and high-level perception begins, the rest of the chapter focuses on the intermediate level of processing, which is implicitly assumed to be the a key component of several perceptual and computational theories (Gibson, 1979; Marr, 1982) and for the visual modality has been termed mid-level vision (see Nakayama, He, & Shimojo, 1995). In particular, we discuss the ability of the perceptual system to specify the position and orientation of environmental objects relative to other objects and especially relative to the observer’s body. We present computational theories and relevant scientific results on individual sense modalities and on the integration of sensory information within and across the sensory modalities. Finally, in the last section of this chapter, we describe how the information processing approach has enabled a better understanding of the perceptual processes in relation to two specific high-level perceptual functions: self-orientation perception and object recognition.nonotspecifiedhttp://www.cyberneum.de/published16Multisensory contributions to spatial perception1501715422Konig20187SUKönigVBrunschMEbertSFleckRGameiroSGasseCGoekeMHanke-UheKKasparJKeyserCKrauseALytochkinRMuilANumonovBSieveritzMSchmitzSWacheSKNagelFSchumannTMeilingerHHBülthoffTWolbersCBüchelPKönigBamberg, Germany2012-10-0013313411th Biannual Meeting of the German Cognitive Science Society (KogWis 2012)Enacted theories of consciousness conjecture that perception and cognition arise from an active experience of the regular relations that tie together sensory stimulation and associated motor actions [1,2]. By employing the technique of sensory substitution [3] and sensory augmentation [4] previous experiments explored this assumption. In this study
a sensory augmentation device delivered global orientation information by mapping directional information of a compass to a set of vibrators around the waist, activating the element pointing north (feelSpace belt) [4]. Here we use it to investigate the impact on cortical plasticity sensory
processing, and spatial cognition. Therefore we want to answer the questions how the brain is able to integrate and use new sensory input, where this processing takes place and whether the newly supplied directional information can be used by the subjects for enhanced orientation and navigation leading to many useful applications. Out of fourteen subjects (age 19–32y, seven female, five controls) nine
were wearing the belts during all waking hours over a period of six weeks. We compared belt-on and belt-off conditions in a series of measurements including homing, fMRI, and subjective methods before, during and after training.
(1) In the homing task using polygons of varying complexity we observed a slight reduction of the systematic error and a larger reduction of the stochastic error in belt-on condition after the training period.
(2) Most areas that were reported in a previous fMRI study on navigation [5] could be replicated in our subjects. Furthermore, we observed widespread cortical activation induced by the belt in the pretraining baseline measurements which is more localized and less intense after training. (3) Subjective reports indicate that by training with the
feelSpace belt the scope of perceived space grows wider and includes areas that are not within reach or directly visible; subjects feel more secure in known as well as previously unknown environments; and navigational
abilities improve and emphasize an egocentric reference frame. The data provide evidence for an integration of the newly supplied signals in sensory integration (homing), cortical processing (fMRI) and spatial cognition (subjective methods). However, further analysis is needed to elucidate significant individual variations.nonotspecifiedhttp://www.cyberneum.de/published1Properties and mechanisms of sensory enhancement1501715422Franchi2012_510AFranchiVenrooij2012_210JVenrooijFMNieuwenhuizenHHBülthoffVenrooij201210JVenrooijFMNieuwenhuizenHHBülthoffFranchi2012_610AFranchiBulthoffN201210HHBülthoffFNieuwenhuizenEndresANG2012_27DEndresRAdamUNoppeneyMAGieseMünchen, Germany2012-09-14166Bernstein Conference 2012Understanding how semantic information is represented in the brain has been an important research focus of neuroscience in the past few years. We showed previously (Endres et al 2010) that Formal Concept Analysis (FCA, (Ganter and Wille 1999)) can reveal interpretable semantic information (e.g. specialization hierarchies, or feature-based representation) from electrophysiological data. Unlike other analysis methods (e.g. hierarchical clustering), FCA does not impose inappropriate structure on the data. FCA is a mathematical formalism compatible with the explicit coding hypothesis (Foldiak, 2009)
Here, we investigate whether similar findings can be obtained from fMRI BOLD responses recorded from human subjects. While the BOLD response provides only an indirect measure of neural activity on a much coarser spatio-temporal scale than electrophysiological recordings, it has the advantage that it can be recorded from humans, which can be questioned about their perceptions during the experiment, thereby obviating the need of interpreting animal behavioural responses. Furthermore, the BOLD signal can be recorded from the whole brain simultaneously.
In our experiment, a single human subject was scanned while viewing 72 grayscale pictures of animate and inanimate objects in a target detection task (Siemens Trio 3T scanner, GE-EPI, TE=40ms, 38 axial slices, TR=3.08s, 48 sessions, amounting to a total of 10,176 volume images). These pictures comprise the formal objects for FCA. We computed formal attributes by learning a hierarchical Bayesian classifier, which maps BOLD responses onto binary features, and these features onto object labels. The connectivity matrix between the binary features and the object labels can then serve as the formal context.
In line with previous reports, FCA revealed a clear dissociation between animate and inanimate objects in a high-level visual area (inferior temporal cortex, IT), with the inanimate category including plants. The inanimate category was subdivided into plants and non-plants when we increased the number of attributes extracted from the fMRI responses. FCA also highlighted organizational differences between the IT and the primary visual cortex, V1. We show that subjective familiarity and similarity ratings are strongly correlated with the attribute structure computed from the fMRI signal.nonotspecifiedhttp://www.cyberneum.de/published-166Explicit coding in the brain: data-driven semantic analysis of human fMRI BOLD responses with Formal Concept Analysis15017154221501718826RoheN2012_37TRoheUNoppeneyMünchen, Germany2012-09-14192193Bernstein Conference 2012Previous research has demonstrated that human observers locate audiovisual (AV) signals in space by averaging auditory (A) and visual (V) spatial signals according to their relative sensory reliabilities (=inverse of variance) (Ernst & Banks, 2002; Alais & Burr, 2004). This form of AV integration is optimal in that it provides the most reliable percept. Yet, the neural systems mediating integration of spatial inputs remain unclear. Multisensory integration of spatial signals has previously been related to higher order association areas such as intraparietal sulcus (IPS) as well as early sensory areas like the planum temporale (Bonath et al., 2007). In the current fMRI study, we investigated whether and how early visual (V1-V3) and higher association (IPS) areas represent A and V spatial information given their retinotopic organization. One subject was presented with synchronous audiovisual signals, at spatially congruent or discrepant locations along the azimuth and at two levels of sensory reliability. Hence, the experimental design factorially manipulated: (1) V location, (2) A location, (3) V reliability. The subject’s task was to localize the A signal. Retinotopic maps in visual areas and IPS were measured with standard wedge and ring checkerboard stimuli. At the behavioral level, the perceived location of the A input was shifted towards the location of the V input depending on the relative A and V reliabilities. At the neural level, the cue locations represented in retinotopic maps were decoded by computing a population vector estimate (Pouget et al., 2000) from the voxels’ BOLD responses to the AV cues given the voxels’ preferred visual field coordinate. In early visual areas (V1-V3), the decoded cue locations were determined by the V spatial signal but were independent from the A spatial signal. In IPS, the decoded cue locations were determined by the V and the A spatial signals if relative V reliability was low. In conclusion, our results suggest that the brain represents AV spatial location in IPS in qualitative agreement with reliability-weighted multisensory integration.nonotspecifiedhttp://www.cyberneum.de/published1Intraparietal sulcus represents audiovisual space15017154221501718826LiFLK20127QLiRWFlemingNKLogothetisGAKelirisMünchen, Germany2012-09-14190Bernstein Conference 2012Perceptual multi-stability is established when the brain fails to reach a single interpretation of the input from the external world. This issue intrigued scientific minds for more than two hundred years. This phenomenon has been found in vision (Leopold & Logothetis, 1999), audition (Repp, 2007), olfaction (Zhou & Chen, 2009) and speech (Warren & Gregory, 1958). Crucial features are similar within and across modalities (Schwarts et al., 2012).
In the visual modality, a number of ambiguous visual patterns have been described such as the Necker cube, motion plaids, and binocular rivalry. Multi-stable stimuli can provide unique insights into visual processing, as changes in perception are decoupled from changes in the stimulus. Understanding of how multi-stable perception occurs might help one to understand visual perception in general.
A key question in multi-stable perception is what the brain processes are responsible in the identification and alternation of the percepts. Some investigators suggest that both top-down and bottom-up processes are involved (García Pérez, 1989) but others argue that multi-stable perception does not need high-level processing but happens automatically as low-level competition between the stimulus features (Akman et al., 2009; Wilson et al, 2000). Furthermore, it is well known that changes in stimulus features can bias perception in one or another direction, (Klink, et al., 2012).
In order to explore this question, we used multi-stable motion stimuli and specifically moving plaids consisting of three superimposed gratings moving in equidistant directions (difference of 120 deg). These stimuli induce the perception of component and pattern motion simultaneously since any two component gratings bind together and are perceived to move in the opposite direction of the third grating component. We modulated properties of the stimuli such as grating speed and size and recorded the responses of human subjects reporting the direction of the single grating using one of three buttons for each direction. Preliminary results show that perceptual dominance is greatly affected by the selection of grating speeds. Grating size did not greatly change the predominance of the different gratings. We find that gratings with speed closer to physiological values have greater probability to be perceived and that gratings with similar speeds tend to group more often than gratings with different speeds. Further manipulations of other stimulus features like contrast and spatial frequency allow parametric variations of the relative probabilities of different interpretations. Our future goal is to use this information to built models of perceptual alternations using probabilistic inference.nonotspecifiedhttp://www.cyberneum.de/published-190Multi-Stable Visual Motion Perception15017154211501715422Bulthoff2012_610HHBülthoffDobrickiMB2012_310MDobrickiBJMohlerHHBülthoffRyll201210MRyllPretto201210PPrettoKonigBEFGGGHKKKLMNSSWNSMBWBK20127SUKönigVBrunschMEbertSFleckRGameiroSGasseCGoekeMHanke-UheKKasparJKeyserCKrauseALytochkinRMuilANumonovBSieveritzMSchmitzSWacheSKNagelFSchumannTMeilingerHHBülthoffTWolbersCBüchelPKönigKloster Seeon, Germany2012-09-0112International Conference Spatial Cognition (SC 2012)nonotspecifiedhttp://www.cyberneum.de/published1Properties and mechanisms of sensory enhancement150171542264593ISYuHSWooHISonWAhnHRJungDYLeeSYYi2012-09-00182621152143Advanced RoboticsThis paper presents a new design and analysis of a haptic interface for a gastrointestinal endoscopy simulation. The gastrointestinal endoscopy is a procedure in which the digestive tract and organs of a patient are diagnosed and treated using a long and flexible endoscope. The developed haptic interface incorporates two degrees of freedom (DOF), each of which is necessary to describe the movements of an endoscope during the actual endoscopy procedures. The haptic interface has a translational motion mechanism to implement the insertion movement of the endoscope, and a rotational motion mechanism to implement the rotational movement of the endoscope. The endoscope included in the haptic interface is supported by a folding guide to prevent the endoscope from buckling. Force feedback in each direction is provided by wire-driven mechanisms. The developed haptic interface has a workspace, sensitivity, and maximum attainable force and torque enough to simulate the endoscopy procedures such as colonoscopy, upper GI (gastrointestinal) endoscopy, and endoscopic retrograde cholangiopancreatography (ERCP). The developed haptic interface is applied to implementation of a colonoscopy simulation. Performance including force bandwidth is evaluated through experiments and simulation.nonotspecifiedhttp://www.cyberneum.de/published28Design of a Haptic Interface for a Gastrointestinal Endoscopy Simulation1501715422BiegBBC20123H-JBiegJ-PBrescianiHHBülthoffLLChuang2012-09-009719PLoS ONERecent studies provide evidence for task-specific influences on saccadic eye movements. For instance, saccades exhibit higher peak velocity when the task requires coordinating eye and hand movements. The current study shows that the need to process task-relevant visual information at the saccade endpoint can be, in itself, sufficient to cause such effects. In this study, participants performed a visual discrimination task which required a saccade for successful completion. We compared the characteristics of these task-related saccades to those of classical target-elicited saccades, which required participants to fixate a visual target without performing a discrimination task. The results show that task-related saccades are faster and initiated earlier than target-elicited saccades. Differences between both saccade types are also noted in their saccade reaction time distributions and their main sequences, i.e., the relationship between saccade velocity, duration, and amplitude.nonotspecifiedhttp://www.cyberneum.de/published8Looking for Discriminating Is Different from Looking for Looking's Sake1501715422FranchiSRBR20123AFranchiCSecchiMRyllHHBülthoffPRobuffo Giordano2012-09-003195768IEEE Robotics & Automation MagazineRobustness and flexibility constitute the main advantages of multiple-robot systems with respect to single-robot ones as per the recent literature. The use of multiple unmanned aerial vehicles (UAVs) combines these benefits with the agility and pervasiveness of aerial platforms [1], [2]. The degree of autonomy of the multi-UAV system should be tuned according to the specificities of the situation under consideration. For regular missions, fully autonomous UAV systems are often appropriate, but, in general, the use of semiautonomous groups of UAVs, supervised or partially controlled by one or more human operators, is the only viable solution to deal with the complexity and unpredictability of real-world scenarios as in, e.g., the case of search and rescue missions or exploration of large/cluttered environments [3]. In addition, the human presence is also mandatory for taking the responsibility of critical decisions in high-risk situations [4].nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/2012f-FraSecRylBueRob-preprint_01.pdfpublished11Shared Control: Balancing Autonomy and Human Assistance with a Group of Quadrotor UAVs1501715422StreuberMBd20123SStreuberBJMohlerHHBülthoffSde la Rosa2012-09-00321281294PresenceTheories of social interaction (i.e., common coding theory) suggest that visual information about the interaction partner is critical for successful interpersonal action coordination. Seeing the interaction partner allows an observer to understand and predict the interaction partner's behavior. However, it is unknown which of the many sources of visual information about an interaction partner (e.g., body, end effectors, and/or interaction objects) are used for action understanding and thus for the control of movements in response to observed actions. We used a novel immersive virtual environment to investigate this further. Specifically, we asked participants to perform table tennis strokes in response to table tennis balls stroked by a virtual table tennis player. We tested the effect of the visibility of the ball, the paddle, and the body of the virtual player on task performance and movement kinematics. Task performance was measured as the minimum distance between the center of the paddle and the center of the ball (radial error). Movement kinematics was measured as variability in the paddle speed of repeatedly executed table tennis strokes (stroke speed variability). We found that radial error was reduced when the ball was visible compared to invisible. However, seeing the body and/or the racket of the virtual players only reduced radial error when the ball was invisible. There was no influence of seeing the ball on stroke speed variability. However, we found that stroke speed variability was reduced when either the body or the paddle of the virtual player was visible. Importantly, the differences in stroke speed variability were largest in the moment when the virtual player hit the ball. This suggests that seeing the virtual player's body or paddle was important for preparing the stroke response. These results demonstrate for the first time that the online control of arm movements is coupled with visual body information about an opponent.nonotspecifiedhttp://www.cyberneum.de/published13The Influence of Visual Information on the Motor Control of Table Tennis Strokes1501715422BastenMM20127KBastenTMeilingerHAMallotKloster Seeon, Germany2012-09-00378385International Conference Spatial Cognition (SC 2012)The interplay of spatial long-term and working memories and the role of oriented and orientation-independent representations is an important but poorly understood issue in spatial cognition. Using a novel priming paradigm, we demonstrate that spatial working memory codes of a given location depend on previous tasks such as mental travels and are thus situated in behavioural context. In two experiments, 136 passersby were asked to sketch an image of a highly familiar city square either without or with prior metal travel, i.e. an imaginated walk along a route crossing the square. With prior mental travel participants drew the sketch more often in the orientation of the imagined route and less often in the orientation found without prior mental travel. This indicates that participants adjusted or selected information from long-term memory according to the situational context. We suggest that orientation priming plays a role in path planning and may facilitate way-finding afterwards. Possible mechanisms of orientation priming are discussed with respect to theories of orientation dependence in spatial memory.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/SC-2012-Basten.pdfpublished7Mental Travel Primes Place Orientation in Spatial Recall1501715422HerdtweckC2012_27CHerdtweckCCurioHamburg, Germany2012-09-00244250IEEE International Conference on Multisensor Fusion and Information Integration (MFI 2012)Estimating heading information reliably from visual cues only is an important goal in human navigation research as well as in application areas ranging from robotics to automotive safety. The focus of expansion (FoE) is deemed to be important for this task. Yet, dynamic and unstructured environments like urban areas still pose an algorithmic challenge. We extend a robust learning framework that operates on optical flow and has at center stage a continuous Latent Variable Model (LVM) [1]. It accounts for missing measurements, erroneous correspondences and independent outlier motion in the visual field of view. The approach bypasses classical camera calibration through learning stages, that only require monocular video footage and corresponding platform motion information. To estimate the FoE we present both a numerical method acting on inferred optical flow fields and regression mapping, e.g. Gaussian-Process regression. We also present results for mapping to velocity, yaw, and even pitch and roll. Performance is demonstrated for car data recorded in non-stationary, urban environments.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/HerdtweckCurioMFI2012.pdfpublished6Monocular Heading Estimation in Non-stationary Urban Environment1501715422NestiMBRBP20127ANestiCMasoneMBarnett-CowanPRobuffo GiordanoHHBülthoffPPrettoParis, France2012-09-002331Driving Simulation Conference Europe 2012Due to limited operational space, in dynamic driving simulators it is common practice to implement motion cueing algorithms that tilt the simulator cabin to reproduce sustained accelerations. In order to avoid conflicting inertial cues, the tilt rate is kept below drivers’ perceptual thresholds, which are typically derived from the results of classical vestibular research where additional sensory cues to self-motion are removed. Here we conduct two experiments in order to assess whether higher tilt limits can be employed to expand the user’s perceptual workspace of dynamic driving simulators. In the first experiment we measure detection thresholds for roll in conditions that closely resemble typical driving. In the second experiment we measure drivers’ perceived realism in slalom driving for sub-, near- and supra-threshold roll rates. Results show that detection threshold for roll in an active driving task is remarkably higher than the limits currently used in motion cueing algorithms to drive simulators. Supra-threshold roll rates in the slalom task are also rated as more realistic. Overall, our findings suggest that higher tilt limits can be successfully implemented in motion cueing algorithms to better optimize simulator operational space.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/DSC-2012-Nest.pdfpublished8Roll rate thresholds and perceived realism in driving simulation1501715422KieferSHG20127MKieferE-JSimHBHelbigMGrafNew Orleans, LA, USA2012-09-00S9752nd Annual Meeting of the Society for Psychophysiological ResearchPerception for action and object recognition are traditionally assumed to depend on distinct brain areas. However, action priming studies showed that action representations facilitate object recognition, suggesting an interaction between dorsal and ventral visual streams.
The present study aimed at further elucidating the role of action representations in visual object recognition using functional magnetic resonance imaging (fMRI) and event-related potentials (ERPs). Short movies showing hands performing an action in interaction with an object (where the object itself was always removed from the video) were shown as primes. The prime movie was followed by a target object affording motor interactions that are either similar (congruent condition) or dissimilar (incongruent condition) to the prime action. Participants had to decide whether an object name shown after the target picture corresponds with the picture or not. At a behavioral level, we found superior accuracy for prime-target pairs with congruent as compared to incongruent actions (action priming). At
a neural level, action priming was associated with reduced activity in a network of parietal and frontal motor regions starting at about 100 ms after target onset. These findings demonstrate that the action priming effect in object recognition arises from rapid access to action representations in motor areas. In line with embodiment theories of conceptual memory, this suggests that knowledge about potential interactions with objects can influence
their recognition within the first 100 ms of perceptual processing.nonotspecifiedhttp://www.cyberneum.de/published0Action Observation Influences Perception: fMRI and ERP Evidence for a Functional Role of Action Representations in Visual Object Recognition1501715422BiegBBC2012_27H-JBiegJ-PBrescianiHHBülthoffLLChuangAlghero, Italy2012-09-0013735th European Conference on Visual PerceptionSmooth pursuit eye movements can be interrupted and resumed at a later stage, eg, when a concurrent task requires visual sampling from elsewhere. Here we address whether and how interruptive saccades are affected by pursuit movements. Our participants pursued an object which moved horizontally in a sinusoidal pattern (frequency: 0.25 Hz, amplitude: 4 deg. visual angle). During this, discrimination targets appeared at 10 deg. eccentricity, to the left or right of the center. They were timed so that they appeared for 1 second while the pursuit object moved either toward or away from the discrimination target's position. Saccade reaction times were earlier when the discrimination targets appeared in a position that the tracking object was moving towards. Interestingly, saccade RTs back to the pursuit object were shorter when the object moved away from the discrimination target. We conclude that interruptions of pursuit movements lead to asymmetries in saccade generation. These asymmetries could have been caused by biases in attention along the predicted pursuit path.nonotspecifiedhttp://www.cyberneum.de/published-137Asymmetries in saccadic latencies during interrupted ocular pursuit1501715422EsinsBKS20127JEsinsIBülthoffIKennerknechtJSchultzAlghero, Italy2012-09-0011335th European Conference on Visual PerceptionCongenital prosopagnosia, the innate impairment in recognizing faces exhibits diverse deficits. Due to this heterogeneity the possible existence of subgroups of the impairment was suggested (eg Kress and Daum, 2003 Behavioural Neurology14109-21). We examined 23 congenital prosopagnosics (cPAs) identified via a screening questionnaire (as used in Stollhoff, Jost, Elze, and Kennerknecht, 2011 PLoS ONE6e15702) and 23 age-, gender and educationally matched controls with a battery consisting of nine different tests. These included well known tests like the Cambridge Face Memory Test (CFMT, Duchaine and Nakayama, 2006 Neuropsychologia44576-85), a Famous Face Test (FFT), and new, own tests about object and face recognition. As expected, cPAs had lower CFMT and FFT scores than the controls. Analyses of the performance patterns across the nine tests suggest the existence of subgroups within both cPAs and controls. These groups could not be revealed only based on the CFMT and FFT scores, indicating the necessity of tests addressing different, specific aspects of object and face perception for the identification of subgroups. Current work focuses on characterizing the subgroups and identifying the most useful tests.nonotspecifiedhttp://www.cyberneum.de/published-113Can a test battery reveal subgroups in congenital prosopagnosia?1501715422ChuangNB20127LChuangFNieuwenhuizenHHBülthoffAlghero, Italy2012-09-009935th European Conference on Visual PerceptionHow are eye-movements planned to access relevant visual information during flight control? From the cockpit perspective, there are two classes of visual information that are relevant for flight control. First, the changing visuals of the external world provide direct perceptual feedback on how the pilot's command of the control stick is affecting the aircraft's current position, orientation and velocity. Second, flight instruments provide abstracted and specific values—on factors such as the aircraft's compass bearing and vertical speed—that have to be continuously monitored, in order for the global objective of certain maneuvers (eg, turns) to be achieved. Trained pilots have to coordinate their eye-movements across this structured visual workspace (ie, outside view and instruments) to access timely and task-relevant information. The current work focuses on providing descriptions of these planned eye-movements. Eye-movements were recorded of pilots in a high-fidelity flight simulator (100° field-of-view) whilst they performed specific flight maneuvers. Fixation durations and transitions between the individual instruments and aspects of the external environment are represented as network graphs. This allowed us to formally describe the sources of information that were relied on across the different tasks and to compare actual performance to expert predictions.nonotspecifiedhttp://www.cyberneum.de/published-99Eye-movement planning during flight maneuvers1501715422KaulardSWBd20127KKaulardJSchultzCWallravenHHBülthoffSde la RosaAlghero, Italy2012-09-0010335th European Conference on Visual PerceptionThe face inversion effect has often been demonstrated in face identification tasks. Less is known about whether processes underlying face expression recognition are also sensitive to face inversion. Face expression recognition is usually investigated using pictures of six emotional expressions. In everyday life, humans are however exposed to a much larger set of facial expressions, which are dynamic. Here, we examine the effect of face inversion on expression recognition for a variety of facial expressions displayed statically and dynamically. We measured participants'recognition accuracy for 12 expressions using a 13 alternative-forced-choice task. We varied the dynamics (videos versus pictures) and the orientation (upright versus inverted) of the presentation of the expressions in a completely crossed design. Accuracy was significantly higher when expressions were presented as videos (62%) than as pictures (47%). Similarly, recognition accuracy was significantly higher for upright (84%) compared to inverted (64%) expressions. Moreover, the effect of orientation changed significantly with expression type. No other effects were significant. This is the first study to report that face inversion affects the recognition of natural facial expressions. Because face inversion effects are interpreted as a sign of configural processing, our results suggest configural processing for a majority of facial expressions.nonotspecifiedhttp://www.cyberneum.de/published-103Inverting natural facial expressions puzzles you1501715422ChuangNB2012_27LLChuangFMNieuwenhuizenHHBülthoffBruxelles, Belgium2012-09-00International Conference on Human-Computer Interaction in Aerospace (HCI-Aero 2012)nonotspecifiedhttp://www.cyberneum.de/published0Investigating Gaze Behavior of Novice Pilots during Basic Flight Maneuvers1501715422GieseCC20127MAGieseEChiovettoCCurioAlghero, Italy2012-09-0015035th European Conference on Visual PerceptionThe idea that complex facial or body movements are composed of simpler components (usually referred to as 'movement primitives'or 'action units') is common in motor control (Chiovetto 2011 Journal of Neurophysiology105(4), 1429-31.) as well as in the study of facial expressions (Ekman and Friesen, 1978). However, such components have rarely been extracted from real facial movement data. Methods: Combining a novel algorithm for anechoic demixing derived from (Omlor and Giese 2011 Journal of Machine Learning Research121111-1148) with a motion retargetting system for 3D facial animation (Curio et al, 2010, MIT Press, 47-65), we estimated spatially and temporally localized components that capture the major part of the variance of dynamic facial expressions. The estimated components were used to generate stimuli for a psychophysical experiment assessing classification rates and emotional expressiveness ratings for stimuli containing combinations of the extracted components. Results: We investigated how the information carried by the different extracted dynamic facial movement components is integrated in facial expression perception. In addition, we tried to apply different cue fusion models to account quantitatively for the obtained experimental results.nonotspecifiedhttp://www.cyberneum.de/published-150Perceptual relevance of kinematic components of facial movements extracted by unsupervised learning1501715422delaRosaMBC20127Sde la RosaSMieskesHHBülthoffCCurioAlghero, Italy2012-09-0024035th European Conference on Visual PerceptionHumans daily physically interact with other people (eg when shaking hands). Understanding the action of others is important for a successful social interaction. Little is known about the visual processes underlying the visual recognition of social interactions. Here we were examined the view dependency of social interaction recognition. We used motion capture to record predefined interactions (eg high five; handshake; hug) acted out by pairs of participants and created 3D models of these interactions. In the actual experiment participants were presented with these interactions one at a time and had to identify a predefined interaction (1IFC task). We manipulated the view point (front, side, top, 45 degree side view) from which participants saw the interaction and the presentation time of the social interactions. We recorded participants'accuracy (as measured by d prime) and reaction time to identify a predefined social interaction. We found that the d primes and reaction time significantly depended on the view point of the social interaction. The results suggest the existence of view dependencies in the visual recognition of social interactions.nonotspecifiedhttp://www.cyberneum.de/published-240View dependencies in the visual recognition of social interactions1501715422EndresANG201210DEndresRAdamUNoppeneyMGieseSchultzFdBK201210JSchultzALFernandez CruzSde la RosaHHBülthoffKKaulardCurioGBd201210CCurioMGieseHHBülthoffSde la RosaRoheWF20123TRoheBWeberKFliessbach2012-08-003362376–2382European Journal of NeuroscienceThe representation of reward anticipation and reward prediction errors is the basis for reward-associated learning. The representation of whether or not a reward occurred (reward receipt) is important for decision making. Recent studies suggest that, while reward anticipation and reward prediction errors are encoded in the midbrain and the ventral striatum, reward receipts are encoded in the medial orbitofrontal cortex. In order to substantiate this functional specialization we analyzed data from an fMRI study in which 59 subjects completed two simple monetary reward paradigms. Because reward receipts and reward prediction errors were correlated, a statistical model comparison was applied separating the effects of the two. Reward prediction error fitted BOLD responses significantly better than reward receipt in the midbrain and the ventral striatum. Conversely, reward receipt fitted BOLD responses better in the orbitofrontal cortex. Activation related to reward anticipation was found in the orbitofrontal cortex. The results confirm a functional specialization of behaviorally important aspects of reward processing within the mesolimbic dopaminergic system.nonotspecifiedhttp://www.cyberneum.de/published-2376Dissociation of BOLD responses to reward prediction errors and reward receipt by a model comparison1501715422150171882664563HISonTBhattacharjeeHHashimoto2012-08-0085932733285IEEE Transactions on Industrial ElectronicsThis paper aims at analyzing the effect of widely known impedance-shaping control method on the perception of soft-tissues in tele-microsurgical applications. The generalized teleoperation control architecture has been modified to include the impedance-shaping term. New performance index has been defined based on the two proposed indices for the detection and the discrimination of the soft environments to analyze the effect of this modified control on the kinesthetic perception of soft-tissues. The effect is then theoretically analyzed on the conventional position-position, force-position, and four-channel control architectures based on the newly defined index. The effectiveness of this newly proposed kinesthetic perception index is also verified using psychophysics experiments. The theoretical analysis of the effects of the impedance-shaping method on the perception of soft tissues is then validated using the proposed index by experiments with phantom soft tissues for conventional teleoperation architectures.nonotspecifiedhttp://www.cyberneum.de/published12Effect of Impedance-Shaping on Perception of Soft Tissues in Macro-Micro Teleoperation1501715422GaissertWFB20123NGaissertSWaterkampRWFlemingIBülthoff2012-08-008717PLoS OneCategorization and categorical perception have been extensively studied, mainly in vision and audition. In the haptic domain, our ability to categorize objects has also been demonstrated in earlier studies. Here we show for the first time that categorical perception also occurs in haptic shape perception. We generated a continuum of complex shapes by morphing between two volumetric objects. Using similarity ratings and multidimensional scaling we ensured that participants could haptically discriminate all objects equally. Next, we performed classification and discrimination tasks. After a short training with the two shape categories, both tasks revealed categorical perception effects. Training leads to between-category expansion resulting in higher discriminability of physical differences between pairs of stimuli straddling the category boundary. Thus, even brief training can alter haptic representations of shape. This suggests that the weights attached to various haptic shape features can be changed dynamically in response to top-down information about class membership.nonotspecifiedhttp://www.cyberneum.de/published6Haptic Categorical Perception of Shape1501715422ConradVN20123VConradMPVitelloUNoppeney2012-08-00823940948Psychological ScienceIn multistable perception, the brain alternates between several perceptual explanations of ambiguous sensory signals. It is unknown whether multistable processes can interact across the senses. In the study reported here, we presented subjects with unisensory (visual or tactile), spatially congruent visuotactile, and spatially incongruent visuotactile apparent motion quartets. Congruent stimulation induced pronounced visuotactile interactions, as indicated by increased dominance times for both vision and touch, and an increased percentage bias for the percept already dominant under unisensory stimulation. Thus, the joint evidence from vision and touch stabilizes the more likely perceptual interpretation and thereby decelerates the rivalry dynamics. Yet the temporal dynamics depended also on subjects’ attentional focus and was generally slower for tactile than for visual reports. Our results support Bayesian approaches to perceptual inference, in which the probability of a perceptual interpretation is determined by combining visual, tactile, or visuotactile evidence with modality-specific priors that depend on subjects’ attentional focus. Critically, the specificity of visuotactile interactions for spatially congruent stimulation indicates multisensory rather than cognitive-bias mechanisms.nonotspecifiedhttp://www.cyberneum.de/published8Interactions Between Apparent Motion Rivalry in Vision and Touch150171542215017188241501718826BiegCFRB20127H-JBiegHHBülthoffLLChuangKonstanz, Germany2012-08-00341344Mensch & Computer (M&C)In der vorliegenden Studie wurde der Einfluss visueller Ablenkung auf Steuerungsaufgaben untersucht. Die Ergebnisse deuten darauf hin, dass bereits eine kurze Verlagerung der Aufmerksamkeit und des Blicks mit einer systematischen Beeinflussung der Steuerungsaufgabe einhergeht. Im Gegenzug findet auch eine systematische Beeinflussung der Augenbewegungen durch die gleichzeitig durchgeführte Steuerungsaufgabe statt. Die Berücksichtigung solcher Interferenzen kann bei der Entwicklung von grafischen On-Board-Informationssystemen für Fahr- oder Flugzeuge von Nutzen sein.nonotspecifiedhttp://www.cyberneum.de/published3Einfluss von Ablenkung und Augenbewegungen auf
Steuerungsaufgaben1501715422OlivariNVBP20127MOlivariFMNieuwenhuizenJVenrooijHHBülthoffLPolliniMinneapolis, MN, USA2012-08-00892914AIAA Modeling and Simulation Technologies Conference 2012The goal of this paper is to better understand how the neuromuscular system of a pilot, or more generally an operator, adapts itself to dierent types of haptic aids during a pitch control task. A multi-loop pilot model, capable of describing the human behaviour during a tracking task, is presented. Three dierent identication techniques were investigated in order to simultaneously identify neuromuscular admittance and the visual response of a
human pilot. In one of them, the various frequency response functions that build up the pilot model are identied using multi-inputs linear time-invariant models in ARX form. A
second method makes use of cross-spectral densities and diagram block algebra to obtain the desired frequency response estimates. The identication techniques were validated using Monte Carlo simulations of a closed-loop control task. Both techniques were compared with the results of another identication method well known in literature and based on cross-spectral density estimates. All those methods were applied in an experimental setup in
which pilots performed a pitch control task with dierent haptic aids. Two dierent haptic aids for tracking task are presented, a Direct Haptic Aid and an Indirect Haptic Aid. The two haptic aids were compared with a baseline condition in which no haptic force was used. The data obtained with the proposed method provide insight in how the pilot adapts his control behavior in relation to dierent haptic feedback schemes. From the experimental results it can be concluded that humans adapt their neuromuscular admittance in relation
with dierent haptic aids. Furthermore, the two new identication techniques seemed to give more reliable admittance estimates.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/Olivari2012.pdfpublished22Multi-loop Pilot Behavior Identification in Response to Simultaneous Visual and Haptic Stimuli1501715422GianiN20127ASGianiUNoppeneyParis, France2012-08-00717218th International Conference on Biomagnetism (BIOMAG 2012)In daily life, our auditory system detects and segregates sounds, derived from complex auditory scenes. Yet, limited processing capacities allow only a small subset of these sounds to enter awareness. This MEG study used informational masking to investigate the neural mechanisms that enable auditory awareness. On each trial, subjects indicated whether they detected a target that was embedded in a multi-tone background in 67% of the trials. Targets were defined as a pair of two 40 Hz amplitude-modulated tones, presented sequentially with a fixed SOA of 1050 ms. Hence, target detection required subjects to perceive both tones within a pair (Fig. 1B). We compared MEG activity for hits and misses separately for target tone 1 and 2 both in sensor and source space (Fig. 1A). Successful target detection was associated with changes in transient evoked source activity in bilateral auditory cortices at 3 stages:
(1) an enhanced M50 component for tone 1,(2)a negative component at ∼ 150ms for tone 2 and (3) a later, long-latency negativity for both tone 1 and 2 at ∼ 300ms (Fig. 1C). Moreover, subjects’ perceptual sensitivity (d) positively correlated with the magnitude of the M150 component. In addition, we investigated whether steady-state activity was modulated by awareness. Indeed, even though all target tones elicited 40 Hz steady-state responses, the amplitude of 40Hz activity was significantly enhanced when subjects became aware of tone 1 and 2.
In conclusion, our results suggest that awareness of a two-tone pair relies on a cascade of processes that segregate this pair from a complex auditory scene. (1) The processing of detected tones is enhanced as indicated by an increased M50 and steady-state response. (2) The sequential integration of the target pair after the 2nd tone then elicits an awareness related negativity at ∼ 150ms.
(3) Finally, aware signals may elicit additional attentional processes, which may be reflected in the enhanced long-latency negativity.nonotspecifiedhttp://www.cyberneum.de/published1Awareness related auditory scene analysis: A processing cascade enables a tone pair to be segregated from background and enter awareness15017154221501718826DobsBCS20127KDobsIBülthoffCCurioJSchultzNaples, FL, USA2012-08-003512th Annual Meeting of the Vision Sciences Society (VSS 2012)Previous research has shown that facial motion can convey information about identity in addition to facial form (e.g. Hill & Johnston, 2001). The present study aims at finding whether identity judgments vary depending on the kinds of facial movements and the task performed. To this end, we used a recent facial motion capture and animation system (Curio et al., 2006). We recorded different actors performing classic emotional facial movements (e.g. happy, sad) and non-emotional facial movements occurring in social interactions (e.g. greetings, farewell). Only non-rigid components of these facial movements were used to animate one single avatar head. In a between-subject design, four groups of participants performed identity judgments based on emotional or social facial movements in a same-different (SD) or a delayed matching-to-sample task (XAB). In the SD task, participants watched two distinct facial movements (e.g. happy and sad) and had to choose whether the same or different actors performed these facial movements. In the XAB task, participants saw one target facial movement X (e.g. happy) performed by one actor followed by two facial movements of another kind (e.g. sad) performed by two actors. Participants chose which of the latter facial movements was performed by the same actor as the one performing X. Prior to the experiment, participants were familiarized with the actors by watching them perform facial movements not subsequently tested. Participants were able to judge actor identities correctly in all conditions, except for the SD task performed on the emotional stimuli. Sensitivity to identity as measured by d-prime was higher in the XAB than in the SD task. Furthermore, performance was higher for social than for emotional stimuli. Our findings reveal an effect of task on identity judgments based on facial motion, and suggest that such judgments are easier when facial movements are less stereotypical.nonotspecifiedhttp://www.cyberneum.de/published-35Investigating factors influencing the perception of identity from facial motion1501715422DobrickiMB20127MDobrickiBJMohlerHHBülthoffNaples, FL, USA2012-08-00132612th Annual Meeting of the Vision Sciences Society (VSS 2012)In the framework of the experimental induction of full-body illusions the features of the experience of being a distinct entity (selfhood) are altered such that participants identify with and mis-localize themselves towards a virtual body. On the other hand, it has been found that the experience of circular self-motion, or vection, can be induced by rotating a naturalistic visual environment around human participants. Circular vection is likely influenced by a person’s self-localization, since it is the illusion of self-rotation around a specific location. Thus, estimates of vection may serve as indicators for altered self-localization. In the framework of a within-subjects design experiment, male participants viewed an avatar from behind within a naturalistic virtual city in a head-mounted display setup. First, we stroked their back for three minutes while they watched the avatar getting synchronously and congruently stroked, or no visuo-tactile stroking was applied (stimulation factor). Subsequently, we assessed their identification with the avatar with a questionnaire, and then repeated the initial treatment. Finally, we rotated the participants’ perspective around their vertical axis for one minute. During rotation the avatar was in the same location in front of the viewer, rotating around his axis, or in a standing posture (avatar-motion factor). Participants were asked to indicate when they started to experience vection. They reported significantly higher identification with the avatar and self-localization in the avatar’s position after visuo-tactile stimulation. Moreover, when they experienced visuo-tactile stimulation, regardless of the avatar-motion factor, participants showed a later onset of vection. One possible explanation for these results is that participants perceived themselves as partially localized in the avatar’s position, and in turn this decrease in their accuracy of self-localization delayed their experience of circular vection. Consequently, we suggest estimates of self-motion as a new measure for selfhood and embodiment, and specifically for self-localization.nonotspecifiedhttp://www.cyberneum.de/published-1326Onset time of visually induced circular self-motion perception as an indicator for altered self-localization in immersive virtual reality1501715422LinkenaugerMPB20127SLinkenaugerBMohlerDProffittHHBülthoffNaples, FL, USA2012-08-0090212th Annual Meeting of the Vision Sciences Society (VSS 2012)The ground plane’s texture gradient is a well-known, perspective depth cue that derives from the fact that, for a uniformly textured surface, texture elements become smaller and more densely arrayed in the visual field with increased in distance e.g. grass on a field or cobble stones on a street. This size / distance relationship also occurs for objects such that objects of equal size occlude an equal amount of texture at their base regardless of their distance from the observer. Texture gradients have been studied primarily as a relative depth cue that specifies the size of one object relative to another. However, more definite relative scaling can be achieved if the size of texture elements is scaled to some known metric. We hypothesized that perceivers use the amount of texture occluded by their own feet to scale the sizes of objects on a textured ground. Using head-mounted displays and a motion capture system, we were able to increase or decrease the apparent size of participants’ visual feet in a virtual environment. We asked participants to verbally estimate the width and height of many objects using meters and centimeters(varying in size at the base). As hypothesized, perceivers’ estimations of the sizes of cylinders were smaller when participants had larger virtual feet and larger when participants had smaller virtual feet. This demonstrates that texture gradient, in combination with the visual self-located body, can be used to estimate the size of objects.nonotspecifiedhttp://www.cyberneum.de/published-902The Role of Visual Foot Size in Perceiving Object Size from Texture Gradient1501715422Bulthoff2012_57IBülthoffNaples, FL, USA2012-08-00128212th Annual Meeting of the Vision Sciences Society (VSS 2012)We can quickly and easily judge faces in terms of their ethnicity. What is the basis for our decision? Other studies have used either eye tracking (e.g., Armann & Bülthoff 2009) or the Bubbles method (e.g., Gosselin & Schyns 2001) in categorization tasks to investigate which facial features are used for sex or identity classification. The first method investigates which parts are preferentially looked at while the latter method shows which facial regions, when shown in isolation during the task, leads to correct classification. Here we measured the influence of facial features on ethnicity classification when they are embedded in the face of the other ethnicity. Asian and Caucasian faces of our 3D face database (http://faces.kyb.tuebingen.mpg.de) had been paired according to sex, age and appearance. We used 18 pairs of those Asian-Caucasian faces to create a variety of mixed-race faces. Mixed-race faces were obtained by exchanging one of the following facial features between both faces of a pair: mouth, nose, facial contour, shape, texture (skin) and eyes. We showed original and modified faces one by one in a simple ethnicity classification task. All faces were turned 20 degrees to the side for a more informative view of nose shape, face shape and facial contour while eyes and mouth and general face textures were still fully visible. Because of skin color differences between exchanged parts and original faces, all 3D faces were rendered as grey-level images. The results of 24 Caucasian participants show that the eyes and the texture of a face are major determinants for ethnicity classification, more than face shape and face contour, while mouth and nose had weak influence. Response times showed that participants were faster at classifying less ambiguous faces.nonotspecifiedhttp://www.cyberneum.de/published-1282What gives a face its ethnicity?1501715422RobuffoGiordano2012_610PRobuffo GiordanoKimESBW201210BRKimJEsinsJSchultzIBülthoffCWallravenRobuffoGiordano2012_710PRobuffo GiordanoNieuwenhuizen201215FMNieuwenhuizen2012-07-04nonotspecifiedpublishedChanges in pilot control behaviour across Stewart platform motion systems1501715422SoykaRBB20113FSoykaPRobuffo GiordanoMBarnett-CowanHHBülthoff2012-07-0012208999Experimental Brain ResearchUnderstanding the dynamics of vestibular perception is important, for example, for improving the realism of motion simulation and virtual reality environments or for diagnosing patients suffering from vestibular problems. Previous research has found a dependence of direction discrimination thresholds for rotational motions on the period length (inverse frequency) of a transient (single cycle) sinusoidal acceleration stimulus. However, self-motion is seldom purely sinusoidal, and up to now, no models have been proposed that take into account non-sinusoidal stimuli for rotational motions. In this work, the influence of both the period length and the specific time course of an inertial stimulus is investigated. Thresholds for three acceleration profile shapes (triangular, sinusoidal, and trapezoidal) were measured for three period lengths (0.3, 1.4, and 6.7 s) in ten participants. A two-alternative forced-choice discrimination task was used where participants had to judge if a yaw rotation around an earth-vertical axis was leftward or rightward. The peak velocity of the stimulus was varied, and the threshold was defined as the stimulus yielding 75 % correct answers. In accordance with previous research, thresholds decreased with shortening period length (from ~2 deg/s for 6.7 s to ~0.8 deg/s for 0.3 s). The peak velocity was the determining factor for discrimination: Different profiles with the same period length have similar velocity thresholds. These measurements were used to fit a novel model based on a description of the firing rate of semi-circular canal neurons. In accordance with previous research, the estimates of the model parameters suggest that velocity storage does not influence perceptual thresholds.nonotspecifiedhttp://www.cyberneum.de/published10Modeling direction discrimination thresholds for yaw rotations around an earth-vertical axis for arbitrary motion profiles1501715422BarnettCowanRB20123MBarnett-CowanSMRaederHHBülthoff2012-07-0012204150Experimental Brain ResearchThe perception of simultaneity between auditory and vestibular information is crucially important for maintaining a coherent representation of the acoustic environment whenever the head moves. It has been recently reported, however, that despite having similar transduction latencies, vestibular stimuli are perceived significantly later than auditory stimuli when simultaneously generated. This suggests that perceptual latency of a head movement is longer than a co-occurring sound. However, these studies paired a vestibular stimulation of long duration (~1 s) and of a continuously changing temporal envelope with a brief (10–50 ms) sound pulse. In the present study, the stimuli were matched for temporal envelope duration and shape. Participants judged the temporal order of the two stimuli, the onset of an active head movement and the onset of brief (50 ms) or long (1,400 ms) sounds with a square- or raised-cosine-shaped envelope. Consistent with previous reports, head movement onset had to precede the onset of a brief sound by about 73 ms in order for the stimuli to be perceived as simultaneous. Head movements paired with long square sounds (~100 ms) were not significantly different than brief sounds. Surprisingly, head movements paired with long raised-cosine sound (~115 ms) had to be presented even earlier than brief stimuli. This additional lead time could not be accounted for by differences in the comparison stimulus characteristics (temporal envelope duration and shape). Rather, differences between sound conditions were found to be attributable to variability in the time for head movement to reach peak velocity: the head moved faster when paired with a brief sound. The persistent lead time required for vestibular stimulation provides further evidence that the perceptual latency of vestibular stimulation is greater than the other senses.nonotspecifiedhttp://www.cyberneum.de/published9Persistent perceptual delay for head movement onset relative to auditory stimuli of different durations and rise times1501715422Bulthoff2012_163IBülthoff2012-07-00741881882Perceptionnonotspecifiedhttp://www.cyberneum.de/published1Review: L'empreinte Des Sens1501715422NethSEKBM2011_23CTNethJLSoumanDEngelUKloosHHBülthoffBJMohler2012-07-0071810411052IEEE Transactions on Visualization and Computer GraphicsRedirected walking techniques allow people to walk in a larger virtual space than the physical extents of the laboratory. We describe two experiments conducted to investigate human sensitivity to walking on a curved path and to validate a new redirected walking technique. In a psychophysical experiment, we found that sensitivity to walking on a curved path was significantly lower for slower walking speeds (radius of 10 m versus 22 m). In an applied study, we investigated the influence of a velocity-dependent dynamic gain controller and an avatar controller on the average distance that participants were able to freely walk before needing to be reoriented. The mean walked distance was significantly greater in the dynamic gain controller condition, as compared to the static controller (22 m versus 15 m). Our results demonstrate that perceptually motivated dynamic redirected walking techniques, in combination with reorientation techniques, allow for unaided exploration of a large virtual city model.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/TVCG_Neth_Manuscript_revised.pdfpublished11Velocity-Dependent Dynamic Curvature Gain for Redirected Walking1501715422Linkenauger20123SLinkenauger2012-07-007-8903233Harvard Business ReviewPeople who believed that a professional golfer had used their club putted more accurately than other people who played with the same club.
Sally Linkenauger and four colleagues recruited 41 right-handed golfers. Each was given a high-end putter and asked to attempt 10 two-meter putts on an artificial green. As they were handed the club, golfers in a randomly chosen group were told that PGA player Ben Curtis had used it, while a control group was told nothing. Before putting, each subject estimated the size of the hole by drawing it. Golfers who believed they were using Curtis’s club estimated the hole to be 9% larger in diameter and sank 32% more putts than the control group did.nonotspecifiedhttp://www.cyberneum.de/published1You'll golf better if you think tiger has used your clubs1501715422McDonnellBB20127RMcDonnellMBreidtHHBülthoffLos Angeles, CA, USA2012-07-0011139th International Conference and Exhibition on Computer Graphics and Interactive Techniques (ACM SIGGRAPH 2012)The realistic depiction of lifelike virtual humans has been the goal of many movie makers in the last decade. Recently, films such as Tron: Legacy and The Curious Case of Benjamin Button have produced highly realistic characters. In the real-time domain, there is also a need to deliver realistic virtual characters, with the increase in popularity of interactive drama video games (such as L.A. Noire™ or Heavy Rain™). There have been mixed reactions from audiences to lifelike characters used in movies and games, with some saying that the increased realism highlights subtle imperfections, which can be disturbing. Some developers opt for a stylized rendering (such as cartoon-shading) to avoid a negative reaction [Thompson 2004]. In this paper, we investigate some of the consequences of choosing realistic or stylized rendering in order to provide guidelines for developers for creating appealing virtual characters. We conducted a series of psychophysical experiments to determine whether render style affects how virtual humans are perceived. Motion capture with synchronized eye-tracked data was used throughout to animate custom-made virtual model replicas of the captured actors.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2013/render_me_real_siggraph2012_small.pdfpublished10Render me Real? Investigating the Effect of Render Style on the Perception of Animated Virtual Humans1501715422EsinsSKWB20127JEsinsJSchultzBRKimCWallravenIBülthoffIncheon, South Korea2012-07-006888th Asia-Pacific Conference on Vision (APCV 2012)Congenital prosopagnosia, an innate impairment in recognizing faces, as well as the other-race-effect, the disadvantage in recognizing faces of foreign races, both influence face recognition abilities.
Here we compared both phenomena by testing three groups: German congenital prosopagnosics (cPs), unimpaired German and unimpaired South Korean participants (n=23 per group), on three tests with Caucasian faces.
First we ran the Cambridge Face Memory Test (Duchaine & Nakayama, 2006 Neuropsychologia 44 576-585). Participants had to recognize Caucasian target faces in a 3AFC task. German controls performed better than Koreans (p=0.009) who performed better than prosopagnosics (p=0.0001). Variation of the individual performances was larger for cPs than for Koreans (p = 0.028).
In the second experiment, participants rated the similarity of Caucasian faces (in-house 3D face-database) which differed parametrically in features or second order relations (configuration). We found differences between sensitivities to change type (featural or configural, p=0) and between groups (p=0.005) and an interaction between both factors (p = 0.019).
During the third experiment, participants had to learn exemplars of artificial objects (greebles), natural objects (shells), and faces and recognize them among distractors. The results showed an interaction (p = 0.005) between stimulus type and participant group: cPs where better for non-face stimuli and worse for face stimuli than the other groups.
Our results suggest that congenital prosopagnosia and the other-race-effect affect face perception in different ways. The broad range in performance for the cPs directs the focus of our future research towards looking for different forms of congenital prosopagnosia.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/APCV-2012-Poster-Esins.pdfpublished-688Comparing the other-race-effect and congenital Prosopagnosia using a three-experiment test battery1501715422HardcastleSLBTK20127BJHardcastleDASchwynKDLongdenKBierigRJTanakaHGKrappCollege Park, MD, USA2012-07-00Tenth International Congress of Neuroethology (ICN 2012)In flying insects the stabilization of gaze aids visual processing by reducing motion blur, for instance, and facilitating self-motion estimation. The gaze control system in blowflies makes use of information from a number of well-characterised sensory modalities, including the compound eyes, ocelli, halteres and campaniform sensilla (Hengstenberg 1991). Individually, these sensory pathways are sensitive to different dynamic ranges, incur different processing delays, and suffer from different levels of sensor and processing noise. Understanding their dynamics and the interplay between them would allow us to study the performance limits of the fly gaze stabilization system, and may advance our understanding of multisensory control architectures in biological systems in general.
We applied a linear systems analysis to roll gaze stabilization in Calliphora based on the frequency responses of the two visual pathways, the compound eyes and the ocelli. In previous studies, stimulation of the ocelli showed little effect on compensatory head movements in the blowfly (Schuppe and Hengstenberg 1993). Recent work at the neuronal level suggests that descending neurons with coupling to neck motor neurons receive input from the ocelli (Haag et al. 2007), and that the ocelli also modulate the activity in optic flow processing interneurons receiving input from the compound eyes (Parsons et al. 2010). Using high speed videography, we measured head roll in response to visual stimulation of both the compound eyes and ocelli, and of the compound eyes alone. The behavioural data were obtained by oscillating a false horizon around the longitudinal body axis at a range of four different input frequencies (1-10Hz) and three amplitudes (10, 20 and 30 degrees). Assuming a linear system, we derived the individual visual pathway frequency responses and obtained the gain and phase plot for the open-loop behaviours corresponding to the two different sensory conditions.
We found that the combination of compound eye and ocellar input reduces the phase in the processing of visual motion information compared to that of the compound eye-mediated response alone (Figure 1B), but does not significantly affect the response gain or bandwidth (Figure 1A). Over the input frequency range investigated, the ocellar contributions lead to an average reduction in the pathway delay of 5.4 ms (SE = 2.5 ms), which is likely to benefit stable and robust feedback control. Our result is consistent with previous studies in locusts which suggest that the ocelli provide a fast response preceding the slower, more precise information from the compound eyes (Taylor 1981). With increasing stimulus amplitudes we observed a reduction in overall response gain, suggesting non-linear saturation effects as the system deviates from its equilibrium point. The influence of the ocelli on the phase of the output, but not on the gain, could also be attributed to non-linearities in the system. Preliminary experiments suggest that other dipteran flies are amenable to a similar behavioural analysis. Future comparative work on the integration of ocellar information and other sensory inputs to gaze control systems across species will help us to derive general principles of multimodal biological control design.nonotspecifiedhttp://www.cyberneum.de/published0Ocellar contributions to gaze control: a behavioural linear systems analysis in the blowfly1501715422JungAB20127WJungRArmannIBülthoffIncheon, South Korea2012-07-006978th Asia-Pacific Conference on Vision (APCV 2012)What gives a face its race?By biological criteria, human “races” do not exist (e.g., Cosmides et al., 2003). Nevertheless, every-day life and research from various fields show that we robustly and reliably perceive humans as belonging to different race groups. Here, we investigate the bases for our quick and easy judgments, by measuring the influence of manipulated facial features on race classification. Asian and Caucasian faces of our 3-dimensional face database (http://faces.kyb.tuebingen.mpg.de) were paired according to sex, age and overall appearance. With these Asian-Caucasian face pairs we created a variety of mixed-race faces, by exchanging facial features between both faces of a pair: eyes, nose, mouth, “outer” features, shape or texture. Original and modified faces were shown in a simple race classification task. We tested 24 Westerners (Germany) and 24 Easterners (South Korea). In both groups, eyes and texture were major determinants for race classification, followed by face shape, and then outer features, mouth, nose, which only had a weak influence on perceived face. Eastern participants classified Caucasian original faces better than Asian original faces, while Western participants were similarly good at classifying both races. Western participants - but not their Eastern counterparts - were less susceptible to eye, shape and texture manipulations in other-race faces than in their own-race faces. A closer look at the data suggests that this effect mainly originates from differences in processing male and female faces in Western participants only. Our results provide more evidence of differences between observers from different cultural and ethnic backgrounds in face perception and processing.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/APCV-2012-Jung.pdfpublished-697What gives a face its race?1501715422BarnettCowan201210MBarnett-CowanSoykaBRB201210FSoykaMBarnett CowanPRobuffo GiordanoHHBülthoffDobrickiMB2012_210MDobrickiBJMohlerHHBülthoffNestiBBP20127ANestiMBarnett-CowanHHBülthoffPPrettoOxford, UK2012-06-2116713th International Multisensory Research Forum (IMRF 2012)The restricted operational space of dynamic driving simulators requires the implementation of motion cueing algorithms that tilt the simulator cabin to reproduce sustained accelerations. In order to avoid conflicting inertial cues, the tilt rate is limited below drivers’ perceptual thresholds, which are typically derived from the results of classical vestibular research, where additional sensory cues to self-motion are removed. These limits might be too conservative for an ecological driving simulation, which provides a variety of complex visual and vestibular cues as well as demands of attention which vary with task difficulty.
We measured roll rate detection threshold in active driving simulation, where visual and vestibular stimuli are provided as well as increased cognitive load from the driving task. Here thresholds during active driving are compared with tilt rate detection thresholds found in the literature (passive thresholds) to assess the effect of the driving task. In a second experiment, these thresholds (active versus passive) are related to driving preferences in a slalom driving course in order to determine which roll rate values are most appropriate for driving simulators so as to present the most realistic driving experience.
The results show that detection threshold for roll in an active driving task is significantly higher than the limits currently used in motion cueing algorithms, suggesting that higher tilt limits can be successfully implemented to better optimize simulator operational space. Supra-threshold roll rates in the slalom task are also rated as more realistic. Overall, our findings indicate that increasing task complexity in driving simulation can decrease motion sensitivity allowing for further expansion of the virtual workspace environment.nonotspecifiedhttp://www.cyberneum.de/published-167Roll rate thresholds in driving simulation1501715422AdamN201210RAdamUNoppeneyNoppeneyASMLWOLC201210UNoppeneyRAdamSSadaghianiJXMaierHLLeeSWernerDOstwaldRLewisVConradBulthoff2012_37SRaederHHBülthoffMBarnett-CowanOxford, UK2012-06-193213th International Multisensory Research Forum (IMRF 2012)The perception of simultaneity between auditory and vestibular information is crucially important for maintaining a coherent representation of the acoustic environment whenever the head moves. Yet, despite similar transduction latencies, vestibular stimuli are perceived significantly later than auditory stimuli when simultaneously generated (Barnett-Cowan and Harris, 2009; 2011). However, these studies paired a vestibular stimulation of long duration (~1 s) and of a continuously changing temporal envelope with brief (10-50 ms) sound pulses. In the present study the stimuli were matched for temporal envelope. Participants judged the temporal order of the onset of an active head movement and of brief (50 ms) or long (1400 ms) sounds with a square or raised-cosine shaped envelope. Consistent with previous reports, head movement onset had to precede the onset of a brief sound by about 73 ms in order to be perceived as simultaneous. Head movements paired with long square sounds (~100ms) were not significantly different than brief sounds. Surprisingly, head movements paired with long raised-cosine sound (~115 ms) had to be presented even earlier than brief stimuli. This additional lead time could not be accounted for by differences in the comparison stimulus characteristics (duration and temporal envelope). Rather, differences among sound conditions were found to be attributable to variability in the time for head movement to reach peak velocity: the head moved faster when paired with a brief sound. The persistent lead time required for vestibular stimulation provides further evidence that the perceptual latency of vestibular stimulation is larger compared to auditory stimuli.nonotspecifiedhttp://www.cyberneum.de/published-32Persistent perceptual delay for head movement onset relative to auditory stimuli of different duration and rise times1501715422ConradVN2012_210VConradMPVitelloUNoppeneyBieg201210H-JBiegSchecklmannTZHGFL201210MSchecklmannSTupakJZellerWHarnischAGianiAJFallgatterBLangguthFranchi2012_310AFranchiRobuffoGiordano2012_810PRobuffo GiordanoBulthoff2012_1310IBülthoffVolkovaM201210EVolkovaAMstislavskiRedcayKS20123ERedcayMKleinerRSaxe2012-06-001696114Frontiers in Human NeuroscienceWhen engaging in joint attention, one person directs another person's attention to an object (Initiating Joint Attention, IJA), and the second person's attention follows (Responding to Joint Attention, RJA). As such, joint attention must occur within the context of a social interaction. This ability is critical to language and social development; yet the neural bases for this pivotal skill remain understudied. This paucity of research is likely due to the challenge in acquiring functional MRI data during a naturalistic, contingent social interaction. To examine the neural bases of both IJA and RJA we implemented a dual-video set-up that allowed for a face-to-face interaction between subject and experimenter via video during fMRI data collection. In each trial, participants either followed the experimenter's gaze to a target (RJA) or cued the experimenter to look at the target (IJA). A control condition, solo attention (SA), was included in which the subject shifted gaze to a target while the experimenter closed her eyes. Block and event-related analyses were conducted and revealed common and distinct regions for IJA and RJA. Distinct regions included the ventromedial prefrontal cortex for RJA and intraparietal sulcus and middle frontal gyrus for IJA (as compared to SA). Conjunction analyses revealed overlap in the dorsal medial prefrontal cortex (dMPFC) and right posterior superior temporal sulcus (pSTS) for IJA and RJA (as compared to SA) for the event analyses. Functional connectivity analyses during a resting baseline suggest joint attention processes recruit distinct but interacting networks, including social-cognitive, voluntary attention orienting, and visual networks. This novel experimental set-up allowed for the identification of the neural bases of joint attention during a real-time interaction and findings suggest that whether one is the initiator or responder, the dMPFC and right pSTS, are selectively recruited during periods of joint attention.nonotspecifiedhttp://www.cyberneum.de/published13Look at this: the neural correlates of initiating and responding to bids for joint attention1501715422ArmannB20113RArmannIBülthoff2012-06-00636980Vision ResearchCategorical perception (CP) is a fundamental cognitive process that enables us to sort similar objects in the world into meaningful categories with clear boundaries between them. CP has been found for high-level stimuli like human faces, more precisely, for the perception of face identity, expression and ethnicity. For sex however, which represents another important and biologically relevant dimension of human faces, results have been equivocal so far. Here, we reinvestigate CP for sex using newly created face stimuli to control two factors that to our opinion might have influenced the results in earlier studies. Our new stimuli are (a) derived from single face identities, so that changes of sex are not confounded with changes of identity information, and (b) “normalized” in their degree of maleness and femaleness, to counteract natural variations of perceived masculinity and femininity of faces that might obstruct evidence of categorical perception. Despite careful normalization, we did not find evidence of CP for sex using classical test procedures, unless participants were specifically familiarized with the face identities before testing. These results support the single-route hypothesis, stating that sex and identity information in faces are not processed in parallel, in contrast to what was suggested in the classical Bruce and Young model of face perception.
Besides, interestingly, our participants show a consistent bias, before and after perceptual normalization of the male–female range of the test morph continua, to judge faces as male rather than female.nonotspecifiedhttp://www.cyberneum.de/published11Male and female faces are only perceived categorically when linked to familiar identities – And when in doubt, he is a male1501715422PasqualettiFB20113FPasqualettiAFranchiFBullo2012-06-00328592606IEEE Transaction on RoboticsThe subject of this paper is the patrolling of an environment with the aid of a team of autonomous agents. We consider both the design of open-loop trajectories with optimal properties and of distributed control laws converging to optimal trajectories. As performance criteria, the refresh time and the latency are considered, i.e., respectively, time gap between any two visits of the same region and the time necessary to inform every agent about an event occurred in the environment. We associate a graph with the environment, and we study separately the case of a chain, tree, and cyclic graph. For the case of chain graph, we first describe a minimum refresh time and latency team trajectory and propose a polynomial time algorithm for its computation. Then, we describe a distributed procedure that steers the robots toward an optimal trajectory. For the case of tree graph, a polynomial time algorithm is developed for the minimum refresh time problem, under the technical assumption of a constant number of robots involved in the patrolling task. Finally, we show that the design of a minimum refresh time trajectory for a cyclic graph is NP-hard, and we develop a constant factor approximation algorithm.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/2010f-FraPasBul-preprint.pdfpublished14On Cooperative Patrolling: Optimal Trajectories, Complexity Analysis, and Approximation Algorithms1501715422GraydonLTP20113MMGraydonSALinkenaugerBTeachmanDRProffitt2012-06-0072613011315Cognition and EmotionInfluences on the perception of affordances (i.e., opportunities for actions) have been primarily studied by manipulating the functional morphology of the body. However, affordances are not just determined by the functional morphology of the perceiver, but also by the physiological state of the perceiver. States of anxiety have been shown to lead to marked changes in individuals' physiological state and their behaviour. To assess the influence of emotional state on affordance perception, the perception of action capabilities in near space was examined after participants completed an anxiety-provoking task. Anxiety was induced immediately prior to tasks that assessed participants' perceived reaching ability in Experiment 1, grasping ability in Experiment 2, and the ability to pass their hands through apertures in Experiment 3. Results indicated that those participants who experienced changes in anxiety underestimated their reaching, grasping, and passing ability compared to non-anxious participants. In other words, anxious participants were more conservative in their estimations of their action capabilities. These results suggest that anxiety influences the perception for affordances in near space and are consistent with the notion that anxiety induces withdrawal behaviours.nonotspecifiedhttp://www.cyberneum.de/published14Scared stiff: The influence of anxiety on the perception of action capabilities1501715422EngelC20127DEngelCCurioAlcalá de Henares, Spain2012-06-00178183IEEE Intelligent Vehicles Symposium (IV 2012)A driver assistance system realizes that the driver is distracted and that a potentially hazardous situation is emerging. Where should it guide the attention of the driver? Optimally to the spot that allows the driver to make the best decision. Pedestrian detectability has been proposed recently as a measure of the probability that a driver perceives pedestrians in an image [9]. Leveraging this information allows a driver assistance system to direct the attention of the driver to the spot that maximizes the probability that all pedestrians are seen. In this paper we extend this concept to dynamic scenes. We use an annotated video dataset recorded from a moving car in an urban environment and acquire the detectabilities of pedestrians via a psychophysical experiment. Based on these measured detectabilites we train a machine learning algorithm to predict detectabilities from a set of image features. We then exploit this mapping to predict the optimal focus of attention in a second experiment, thus demonstrating the usefulness of our method in a dynamic driver assistance context.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/IV2012-Engel.pdfpublished5Detectability prediction in dynamic scenes for enhanced environment perception1501715422ChoSARJ20127JHChoHISonMAnnerstedtARobertssonRJohanssonRoma, Italy2012-06-0075804th IEEE RAS & EMBS International Conference on Biomedical Robotics and Biomechatronics (BioRob 2012)A suturing including knot tying is one of the more difficult operations to learn in telesurgical systems. Apprentice surgeons commonly suffer from suture breakage or knot failure. The difficulty, generally, comes from the absence of feedback of interaction force cues in a medical device (e.g., a needle and a thread). Even if there is haptic feedback to the operator, the operator may have a difficulty to detect a specific force such as suture breakage force. To deal with this problem, we propose a control method which can detect a suture breakage force more sensitively by considering human perception characteristics. A performance objective of the control method is designed according to the human perceptual factor, just noticeable difference. By convex optimization of the performance indices, a stabilizing H∞ controller is proposed for the telesurgical system. Finally, the proposed control scheme is validated via a simulation study.nonotspecifiedhttp://www.cyberneum.de/published5Enhancement of human operator's perceptual sensitivity for telesurgical systems via polytopic system approach1501715422HerdtweckC20127CHerdtweckCCurioAlcalá de Henares, Spain2012-06-00661667IEEE Intelligent Vehicles Symposium (IV 2012)Visual odometry has been promoted as a fundamental component for intelligent vehicles. Relying solely on monocular image cues would be desirable. Nevertheless, this is a challenge especially in dynamically varying urban areas due to scale ambiguities, independent motions, and measurement noise. We propose to use probabilistic learning with auxiliar depth cues. Specifically, we developed an expert model that specializes monocular egomotion estimation units on typical scene structures, i.e. statistical variations of scene depth layouts. The framework adaptively selects the best fitting expert. For on-line estimation of egomotion, we adopted a probabilistic subspace flow estimation method. Learning in our framework consists of two components: 1) Partitioning of datasets of video and ground truth odometry data based on unsupervised clustering of dense stereo depth profiles and 2) training a cascade of subspace flow expert models. A probabilistic quality measure from the estimates of the experts provides a selection rule overall leading to improvements of egomotion estimation for long test sequences.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/IV-2012-Herdtweck-Curio.pdfpublished6Experts of probabilistic flow subspaces for robust monocular odometry in urban areas1501715422SoykaBRB2012_210FSoykaMBarnett-CowanPRobuffo GiordanoHHBülthoffBulthoff2012_410HHBülthoffMuryyWF20127AAMuryyAWelchmanRWFlemingCambridge, UK2012-05-22192nd Joint AVA/BMVA Meeting on Biological and Machine VisionThe disparity fields created by matte surfaces match the surface's true depth profile. However, for specular surfaces the disparities are shifted away from the surface, tracing out virtual ('antanaclastic') surfaces in depth. Previous studies (Blake & Bülthoff, 1990, Nature, 343, 165; Wendt et al, 2008, doi:10.1167/8.1.14) showed that surfaces appear glossier and more realistic if highlight disparities are physically correct. But which specific binocular cues does the visual system use to identify specularities? We computationally analyzed disparity fields generated by irregularly-shaped objects and found that statistics of vertical disparities (VD) and horizontal disparity gradients (HDG) of specular shapes are qualitatively different from Lambertian surfaces. For specular surfaces, the distributions are heavy-tailed, containing large values that often exceed fusibility limits. This suggests specific binocular cues that the visual system could use for distinguishing glossy and matte materials. In order to test whether these disparity cues affect perceived glossiness, we developed stimuli that allow us to vary disparity fields continuously from perfectly specular to matte and beyond to ‘super glossy’ by varying a single parameter ('virtual IPD'). vIPD parameter defines position of ‘virtual eyes’ on the inter-ocular axis; left and right images are rendered by mapping the illumination on the surface through reflection process due to ‘virtual’ eyes, thus creating left and right virtual reflections while real cameras remain at same positions. We measured gloss discrimination (N = 5) and found that above vIPD = 0.37 human observers perceived stimuli to be as glossy as physically correct mirror stimuli (vIPD=1, ‘virtual eyes’ coincide with real cameras), and below vIPD=0.07 stimuli were perceived as matte as Lambertian (vIPD=0, ‘virtual eyes’ coincide with
cyclopean point, left and right reflection patterns are the same). This suggests the brain does not 'know the physics of specular reflection' but instead relies on specific binocular cues.nonotspecifiedhttp://www.cyberneum.de/published-19Binocular cues for glossiness1501715422ThorntonHB20127IMThorntonTSHorowitzHHBülthoffCambridge, UK2012-05-22162nd Joint AVA/BMVA Meeting on Biological and Machine VisionThis presentation will summarise recent work in which we have been exploiting the display, interface and data collection potential of mobile devices such as the iPad. In one series of experiments we have implemented the MILO task (Thornton & Horowitz, 2004 Perception & Psychophysics 66 38-50) as a simple app and shown how it can be used to explore future planning during sequential search. In a second series of experiments we explore how passive and active tracking of multiple targets might be related. Finally, we exploit the tilt control of the iPad to examine whether action eliminates errors in displays that cause motion-induced illusory displacement. In addition to standard behavioural measures, we will also consider how indirect measures, such as posture and applied force can be easily acquired during data collection. The potential for conducting remote, large-scale studies will also be discussed.nonotspecifiedhttp://www.cyberneum.de/published-16Searching, Tracking & Control using the iPad1501715422Franchi201210AFranchiFranchi2012_210AFranchiSon201210HISonRobuffoGiordano201210PRobuffo GiordanoRobuffoGiordano2012_310PRobuffo GiordanoRuddleVB201210RRuddleEVolkovaHHBülthoffChuangVB2012_23LLChuangQCVuongHHBülthoff2012-05-0026618Frontiers in Computational NeuroscienceThere is evidence that observers use learned object motion to recognize objects. For instance, studies have shown that reversing the learned direction in which a rigid object rotated in depth impaired recognition accuracy. This motion reversal can be achieved by playing animation sequences of moving objects in reverse frame order. In the current study, we used this sequence-reversal manipulation to investigate whether observers encode the motion of dynamic objects in visual memory, and whether such dynamic representations are encoded in a way that is dependent on the viewing conditions. Participants first learned dynamic novel objects, presented as animation sequences. Following learning, they were then tested on their ability to recognize these learned objects when their animation sequence was shown in the same sequence order as during learning or in the reverse sequence order. In Experiment 1, we found that non-rigid motion contributed to recognition performance; that is, sequence-reversal decreased sensitivity across different tasks. In subsequent experiments, we tested the recognition of non-rigidly deforming (Experiment 2) and rigidly rotating (Experiment 3) objects across novel viewpoints. Recognition performance was affected by viewpoint changes for both experiments. Learned non-rigid motion continued to contribute to recognition performance and this benefit was the same across all viewpoint changes. By comparison, learned rigid motion did not contribute to recognition performance. These results suggest that non-rigid motion provides a source of information for recognizing dynamic objects, which is not affected by changes to viewpoint.nonotspecifiedhttp://www.cyberneum.de/published7Learned non-rigid object motion is a view-invariant cue to recognizing novel objects1501715422BarnettCowanMVTB20113MBarnett-CowanTMeilingerMVidalHTeufelHHBülthoff2012-05-006316Journal of Visualized ExperimentsPath integration is a process in which self-motion is integrated over time to obtain an estimate of one's current position relative to a starting point 1. Humans can do path integration based exclusively on visual 2-3, auditory 4, or inertial cues 5. However, with multiple cues present, inertial cues - particularly kinaesthetic - seem to dominate 6-7. In the absence of vision, humans tend to overestimate short distances (<5 m) and turning angles (<30°), but underestimate longer ones 5. Movement through physical space therefore does not seem to be accurately represented by the brain.
Extensive work has been done on evaluating path integration in the horizontal plane, but little is known about vertical movement (see 3 for virtual movement from vision alone). One reason for this is that traditional motion simulators have a small range of motion restricted mainly to the horizontal plane. Here we take advantage of a motion simulator 8-9 with a large range of motion to assess whether path integration is similar between horizontal and vertical planes. The relative contributions of inertial and visual cues for path navigation were also assessed.
16 observers sat upright in a seat mounted to the flange of a modified KUKA anthropomorphic robot arm. Sensory information was manipulated by providing visual (optic flow, limited lifetime star field), vestibular-kinaesthetic (passive self motion with eyes closed), or visual and vestibular-kinaesthetic motion cues. Movement trajectories in the horizontal, sagittal and frontal planes consisted of two segment lengths (1st: 0.4 m, 2nd: 1 m; ±0.24 m/s2 peak acceleration). The angle of the two segments was either 45° or 90°. Observers pointed back to their origin by moving an arrow that was superimposed on an avatar presented on the screen.
Observers were more likely to underestimate angle size for movement in the horizontal plane compared to the vertical planes. In the frontal plane observers were more likely to overestimate angle size while there was no such bias in the sagittal plane. Finally, observers responded slower when answering based on vestibular-kinaesthetic information alone. Human path integration based on vestibular-kinaesthetic information alone thus takes longer than when visual information is present. That pointing is consistent with underestimating and overestimating the angle one has moved through in the horizontal and vertical planes respectively, suggests that the neural representation of self-motion through space is non-symmetrical which may relate to the fact that humans experience movement mostly within the horizontal plane.nonotspecifiedhttp://www.cyberneum.de/published5MPI CyberMotion Simulator: Implementation of a Novel Motion Simulator to Investigate Multisensory Path Integration in Three Dimensions1501715422CamposBB20123JLCamposJSButlerHHBülthoff2012-05-004218551565Experimental Brain ResearchWhen walking through space, both dynamic visual information (optic flow) and body-based information (proprioceptive and vestibular) jointly specify the magnitude of distance travelled. While recent evidence has demonstrated the extent to which each of these cues can be used independently, less is known about how they are integrated when simultaneously present. Many studies have shown that sensory information is integrated using a weighted linear sum, yet little is known about whether this holds true for the integration of visual and body-based cues for travelled distance perception. In this study using Virtual Reality technologies, participants first travelled a predefined distance and subsequently matched this distance by adjusting an egocentric, in-depth target. The visual stimulus consisted of a long hallway and was presented in stereo via a head-mounted display. Body-based cues were provided either by walking in a fully tracked free-walking space (Exp. 1) or by being passively moved in a wheelchair (Exp. 2). Travelled distances were provided either through optic flow alone, body-based cues alone or through both cues combined. In the combined condition, visually specified distances were either congruent (1.0×) or incongruent (0.7× or 1.4×) with distances specified by body-based cues. Responses reflect a consistent combined effect of both visual and body-based information, with an overall higher influence of body-based cues when walking and a higher influence of visual cues during passive movement. When comparing the results of Experiments 1 and 2, it is clear that both proprioceptive and vestibular cues contribute to travelled distance estimates during walking. These observed results were effectively described using a basic linear weighting model.nonotspecifiedhttp://www.cyberneum.de/published14Multisensory integration in the estimation of walked distances1501715422NolanBWFBR20113HNolanJSButlerRWhelanJJFoxeHHBülthoffRBReilly2012-05-001219111Experimental Brain ResearchThe perception of self-motion is a product of the integration of information from both visual and non-visual cues, to which the vestibular system is a central contributor. It is well documented that vestibular dysfunction leads to impaired movement and balance, dizziness and falls, and yet our knowledge of the neuronal processing of vestibular signals remains relatively sparse. In this study, high-density electroencephalographic recordings were deployed to investigate the neural processes associated with vestibular detection of changes in heading. To this end, a self-motion oddball paradigm was designed. Participants were translated linearly 7.8 cm on a motion platform using a one second motion profile, at a 45° angle leftward or rightward of straight ahead. These headings were presented with a stimulus probability of 80–20 %. Participants responded when they detected the infrequent direction change via button-press. Event-related potentials (ERPs) were calculated in response to the standard (80 %) and target (20 %) movement directions. Statistical parametric mapping showed that ERPs to standard and target movements differed significantly from 490 to 950 ms post-stimulus. Topographic analysis showed that this difference had a typical P3 topography. Individual participant bootstrap analysis revealed that 93.3 % of participants exhibited a clear P3 component. These results indicate that a perceived change in vestibular heading can readily elicit a P3 response, wholly similar to that evoked by oddball stimuli presented in other sensory modalities. This vestibular-evoked P3 response may provide a readily and robustly detectable objective measure for the evaluation of vestibular integrity in various disease models.nonotspecifiedhttp://www.cyberneum.de/published10Neural correlates of oddball detection in self-motion heading: A high-density event-related potential study of vestibular integration1501715422SonO20113HISonMHOh2012-05-002226178183Proceedings of the Institution of Mechanical Engineering, Part E: Journal of Process Mechanical EngineeringIn this article, an automatic detection and judgement method for macro defects in thin film transistor (TFT) fabrication process is proposed using a high-resolution line charge-coupled device camera as a preliminary inspection method for TFT liquid crystal display (TFT-LCD) panel. Macro defects are classified primarily into four types. Relevant detection and judgement methods are then applied according to the type of macro defect using different criteria such as diffraction pattern shifts, just noticeable differences, and the gradient of inspection images. The proposed method is verified with industrial experiments. In the experiment, 559 TFT glasses are used, which are sampled among the glasses and were judged as PASS (i.e. non-killer-defected glass) in the TFT fabrication process by a conventional human inspection method, but were judged as REJECT (i.e. killer-defected glass) in the module process. All macro defects in the sampled glasses were detected and rejected in the TFT fabrication process using the proposed method.nonotspecifiedhttp://www.cyberneum.de/published5Real-time automatic inspection of macro defects in in-line TFT fabrication process1501715422CognettiSFOB20127MCognettiPStegagnoAFranchiGOrioloHHBülthoffSt. Paul, MN, USA2012-05-00791798IEEE International Conference on Robotics and Automation (ICRA 2012)We present a decentralized algorithm for estimating mutual 3-D poses in a group of mobile robots, such as a team of UAVs. Our algorithm uses bearing measurements reconstructed, e.g., by a visual sensor, and inertial measurements coming from the robot IMU. Since identification of a specific robot in a group would require visual tagging and may be cumbersome in practice, we simply assume that the bearing measurements are anonymous. The proposed localization method is a non-trivial extension of our previous algorithm for the 2-D case [1], and exhibits similar performance and robustness. An experimental validation of the algorithm has been performed using quadrotor UAVs.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/2012c-CogSteFraOriBue.pdfpublished73-D Mutual Localization with Anonymous Bearing Measurements1501715422BrowatzkiTMBW20127BBrowatzkiVTikhanoffGMettaHHBülthoffCWallravenSt. Paul, MN, USA2012-05-0020212028IEEE International Conference on Robotics and Automation (ICRA 2012)Interaction with its environment is a key requisite for a humanoid robot. Especially the ability to recognize and manipulate unknown objects is crucial to successfully work in natural environments. Visual object recognition, however, still remains a challenging problem, as three-dimensional objects often give rise to ambiguous, two-dimensional views. Here, we propose a perception-driven, multisensory exploration and recognition scheme to actively resolve ambiguities that emerge at certain viewpoints. We define an efficient method to acquire two-dimensional views in an object-centered task space and sample characteristic views on a view sphere. Information is accumulated during the recognition process and used to select actions expected to be most beneficial in discriminating similar objects. Besides visual information we take into account proprioceptive information to create more reliable hypotheses. Simulation and real-world results clearly demonstrate the efficiency of active, multisensory exploration over passive, visiononly recognition methods.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/ICRA-2012-Browatzki.pdfpublished7Active Object Recognition on a Humanoid Robot1501715422SecchiFBP20127CSecchiAFranchiHHBülthoffPRobuffo GiordanoSt. Paul, MN, USA2012-05-0043074314IEEE International Conference on Robotics and Automation (ICRA 2012)In this paper, we present a passivity-based decentralized approach for bilaterally teleoperating a group of UAVs composing the slave side of the teleoperation system. In particular, we explicitly consider the presence of time delays, both among the master and slave, and within UAVs composing the group. Our focus is on analyzing suitable (passive) strategies that allow a stable teloperation of the group despite presence of delays, while still ensuring high flexibility to the group topology (e.g., possibility to autonomously split or join during the motion). The performance and soundness of the approach is validated by means of human/hardware-in-the-loop simulations (HHIL).nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/ICRA-2012-Secchi.pdfpublished7Bilateral teleoperation of a group of UAVs with communication delays and switching topology1501715422VenrooijYPQJM20117JVenrooijDYilmazMDPavelGQuarantaMJumpMMulderVergiate, Gallarate, Italy2012-05-0095896737th European Rotorcraft Forum (ERF 2011)Biodynamic feedthrough (BDFT) refers to a phenomenon where vehicle accelerations cause involuntary pilot limb motions which, when coupled to a control device, can result in unintentional control inputs. It is known that BDFT occurs in helicopters, amongst many other vehicles. The goal of the current study is to analyze the pilot’s response to helicopter motion and experimentally determine the level of BDFT occurring in helicopters.
In this study, BDFT was measured for the collective and the cyclic control devices, in roll, pitch, and vertical direction, for three different control tasks, a position task (PT) or ’stiff task’, a force task (FT) or ’compliant task’, and a relax task (RT). The study focuses on the influence of the pilot’s neuromuscular dynamics on the level of BDFT. Two major conclusions can be drawn from the experimental results: 1) BDFT in helicopters is task dependent 2) the highest level of BDFT is measured in lateral direction, followed by longitudinal and finally vertical direction.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/ERF-2011-Venrooij.pdfpublished9Measuring biodynamic feedthrough in helicopters1501715422RyllBR2012_27MRyllHHBülthoffPRobuffo GiordanoSt. Paul, MN, USA2012-05-0046064613IEEE International Conference on Robotics and Automation (ICRA 2012)Standard quadrotor UAVs possess a limited mobility because of their inherent underactuation, i.e., availability of 4 independent control inputs (the 4 propeller spinning velocities) vs. the 6 dofs parameterizing the quadrotor position/ orientation in space. As a consequence, the quadrotor pose cannot track an arbitrary trajectory over time (e.g., it can hover on the spot only when horizontal). In this paper, we propose a novel actuation concept in which the quadrotor propellers are allowed to tilt about their axes w.r.t. the main quadrotor body. This introduces an additional set of 4 control inputs which provides full actuation to the quadrotor position/orientation. After deriving the dynamical model of the proposed quadrotor, we formally discuss its controllability properties and propose a nonlinear trajectory tracking controller based on dynamic feedback linearization techniques. The soundness of our approach is validated by means of simulation results.nonotspecifiedhttp://www.cyberneum.de/published7Modeling and Control of a Quadrotor UAV with Tilting Propellers1501715422JumpPPWFFZSSBDSMHNB20117MJumpPPerfectGDPadfieldMDWhiteDFloreanoPFuaJ-CZuffereyFSchillRSiegwartSBouabdallahMDeckerJSchipplSMayerMHöfingerFMNieuwenhuizenHHBülthoffVergiate, Gallarate, Italy2012-05-0033634737th European Rotorcraft Forum (ERF 2011)This paper describes the European Commission (EC) Framework 7 funded project myCopter (2011-2014). The project is still at an early stage so the paper starts with the current transportation issues faced by developed countries and describes a means to solve them through the use of personal aerial transportation. The concept of personal air vehicles (PAV) is briefly reviewed and how this project intends to tackle the problem from a different perspective described. It is argued that the key reason that many PAV concepts have failed is because the operational infrastructure and socio-economic issues have not been properly addressed; rather, the start point has been the design of the vehicle itself. Some of the key aspects that would make a personal aerial transport system (PATS) viable include the required infrastructure and associated technologies, the skill levels and machine interfaces needed by the occupant or pilot and the views of society as a whole on the acceptability of such a proposition. The myCopter project will use these areas to explore the viability of PAVs within a PATS. The paper reports upon the early progress made within the project. An initial reference set of PAV requirements has been collated. A non-physical flight simulation model capable of providing a wide range of handling qualities characteristics has been developed and its function has undergone limited verification. Results from this exercise show that the model behaves as intended and that it can deliver a predictable range of vehicle dynamics. The future direction of the themes of work described within the paper are then described.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/ERF2011_122.pdfpublished11MyCopter: Enabling Technologies for Personal Air Transport Systems1501715422GrabeBR2012_27VGrabeHHBülthoffPRobuffo GiordanoSt. Paul, MN, USA2012-05-00491497IEEE International Conference on Robotics and Automation (ICRA 2012)Robot vision became a field of increasing importance in micro aerial vehicle robotics with the availability of small and light hardware. While most approaches rely on external ground stations because of the need of high computational power, we will present a full autonomous setup using only on-board hardware. Our work is based on the continuous homography constraint to recover ego-motion from optical flow. Thus we are able to provide an efficient fall back routine for any kind of UAV (Unmanned Aerial Vehicles) since we rely solely on a monocular camera and on on-board computation. In particular, we devised two variants of the classical continuous 4-point algorithm and provided an extensive experimental evaluation against a known ground truth. The results show that our approach is able to recover the ego-motion of a flying UAV in realistic conditions and by only relying on the limited on-board computational power. Furthermore, we exploited the velocity estimation for closing the loop and controlling the motion of the UAV online.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/ICRA2012-Grabe.pdfpublished6On-board velocity estimation and closed-loop control of a quadrotor UAV based on optical flow1501715422QuarantaMV20127GQuarantaPMasaratiJVenrooijFort Worth, TX, USA2012-05-001306131568th American Helicopter Society International Annual Forum (AHS 2012)Biodynamic feedthrough (BDFT) may significantly affect the closed-loop behavior of rotorcraft, reducing the stability and increasing the proneness to Rotorcraft-Pilot Couplings (RPC). Leveraging robust stability analysis, the inherently uncertain pilot BDFT can be treated as the uncertain portion of a feedback system, allowing analytical, numerical or graphical determination of proneness to RPC by comparing robust stability margins of helicopter models with BDFT data. The application of the proposed approach to collective bounce is exemplified using simple analytical helicopter and pilot BDFT models, and applied to detailed helicopter models and BDFT measurement data.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/AHS-2012-Quaranta.pdfpublished9Robust Stability Analysis: a Tool to Assess the Impact of Biodynamic Feedthrough on Rotorcraft1501715422LeeB201246J-JLeeHHBülthoff2012-05-002012-05-00Helilab User Manual: Human Behavior and Flight Data
Acquisition and AnalysisnonotspecifiedHelilab User Manual: Human Behavior and Flight Data
Acquisition and Analysis1501715422PerdikisMKWL20127DPerdikisVMüllerKKaulardCWallravenULindenbergMarseille, France2012-05-001st Conference of the European Society for Cognitive and Affective Neuroscience (ESCAN 2012)Humans recognize facial emotional expressions (FEEs) better when FEEs are presented dynamically than through static images. Wallraven et al. 2008 propose that humans are sensitive to the natural dynamics of FEEs. Moreover, PET/fMRI studies suggest that differentiated brain networks process static and dynamic FEEs. However, in most cases, dynamic FEEs have been created out of static ones, using linear morphing techniques. Together with the low time resolution of PET/fMRI, such studies fail to capture the modulation of the activated brain networks by the subtle (and highly nonlinear) dynamics of FEEs. Our ongoing study investigates EEG responses to static and dynamic FEEs drawn from an ecologically valid database (Kaulard et al. 2008, Kaulard et al. 2009). “Happy” and “angry” FEEs performed by two male and two female actors are displayed to twenty female participants in an “oddball” experimental paradigm. Blocks of either dynamic or static stimuli that differ in their emotional content (“happy” versus “angry” and reverse) are presented in a pseudorandom order. The task consists of pressing a keyboard button upon appearance of a deviant stimulus. Data analysis focuses on synchrony and nonlinear coupling of sensor as well as source dynamics (as a bridge to PET/fMRI studies), both in the time-frequency and in the phase-space domain, to identify the brain networks that emerge and evolve dynamically in each condition. Preliminary results from pilot data analysis confirm the PET/fMRI findings of enhanced and differentiated brain activations for dynamic FEEs compared to static ones.nonotspecifiedhttp://www.cyberneum.de/published0EEG brain dynamics during processing of static and dynamic facial emotional expression1501715422RobuffoGiordano2012_210PRobuffo GiordanoWittLP20123JKWittSALinkenaugerDRProffitt2012-04-00423397399Psychological ScienceOne of the reasons we (the authors) enjoy going to live college basketball games is to watch the antics of the student section. We love watching the students’ creativity in trying to pump up the home team and distract the visiting team, especially during free throws. Such escapades made us question whether manipulating what athletes see can influence their subsequent performance.
Perception is clearly important for performance. For instance, when athletes look directly at a target without moving their eyes around—a pattern known as the quiet eye—they are more successful in making free throws, putting, and performing a variety of other tasks (e.g., Vickers, 1996, 2007). The quiet eye might lead to more successful performance by focusing attention on targets, and helping athletes to ignore distractors. Additionally, the quiet eye might change the way targets look. Targets presented in the fovea look bigger than those in the periphery (Newsome, 1972), so the quiet eye might lead athletes to perceive targets as bigger.
Misperceiving a target as bigger could influence performance in one of three ways. It could disrupt performance because the observer might aim for a location that does not correspond with the target. In this case, the misperception would result in worse performance. However, actions and explicit perceptions may not be influenced by illusions to the same degree (Goodale & Milner, 1992). That is, there may be dissociations between perceptions and visually guided actions such that illusions, which fool conscious perception, do not influence subsequent actions (e.g., Ganel, Tanzer, & Goodale, 2008). In this case, misperceiving a target as bigger would not affect performance. A final alternative is that misperceiving a target as bigger could enhance performance. Bigger targets feel as if they should be easier to hit, so people may feel more confident when aiming for a bigger target. Given that increased confidence improves performance (e.g., Woodman & Hardy, 2003), a perceptually bigger target may also lead to enhanced performance. Here, we report an experiment in which we tested these possibilities.nonotspecifiedhttp://www.cyberneum.de/published2Get Me Out of This Slump! Visual Illusions Improve Sports Performance1501715422vonLassbergBCK20123Cvon LassbergKBeykirchJLCamposJKrug2012-04-00216176194Motor ControlThis study investigated long-term adaptations of smooth pursuit eye movement characteristics in high-level gymnasts and compared these responses to those of nonathletes. Gymnasts were selected because of their exceptional ability to spatially orient during fast, multiaxial whole body rotations. Participants were tested with standardized and supra-maximal sinusoidal smooth pursuit measurements. The results showed significantly higher gain values in top-level gymnasts, followed by young federal team gymnasts, followed by the nonathlete control group. By testing participants over the course of three years and also after periods of abstinence from training, changes to patterns of smooth pursuit over time are revealed. These results have interesting implications for understanding the characteristics of eye-movements in expert populations as well as understanding the general principles that underlie oculomotor adaptation.nonotspecifiedhttp://www.cyberneum.de/published18Smooth Pursuit Eye Movement Adaptation in High Level Gymnasts1501715422GianiOBKPN20123ASGianiEBOrtizPBelardinelliMKleinerHPreisslUNoppeney2012-04-002601478–1489NeuroImageTo form a unified percept of our environment, the human brain integrates information within and across the senses. This MEG study investigated interactions within and between sensory modalities using a frequency analysis of steady-state responses that are elicited time-locked to periodically modulated stimuli. Critically, in the frequency domain, interactions between sensory signals are indexed by crossmodulation terms (i.e. the sums and differences of the fundamental frequencies). The 3x2 factorial design, manipulated (1) modality: auditory, visual or audiovisual (2) steady-state modulation: the auditory and visual signals were modulated only in one sensory feature (e.g. visual gratings modulated in luminance at 6 Hz) or in two features (e.g. tones modulated in frequency at 40 Hz & amplitude at 0.2 Hz). This design enabled us to investigate crossmodulation frequencies that are elicited when two stimulus features are modulated concurrently (i) in one sensory modality or (ii) in auditory and visual modalities. In support of within-modality integration, we reliably identified crossmodulation frequencies when two stimulus features in one sensory modality were modulated at different frequencies. In contrast, no crossmodulation frequencies were identified when information needed to be combined from auditory and visual modalities. The absence of audiovisual crossmodulation frequencies suggests that the previously reported audiovisual interactions in primary sensory areas may mediate low level spatiotemporal coincidence detection that is prominent for stimulus transients but less relevant for sustained SSR responses. In conclusion, our results indicate that information in SSRs is integrated over multiple time scales within but not across sensory modalities at the primary cortical level.nonotspecifiedhttp://www.cyberneum.de/published-1478Steady-state responses in MEG demonstrate information integration within but not across the auditory and visual senses15017188261501715422FischerLBB20113EFischerNKLogothetisHHBülthoffABartels2012-04-00422865876Cerebral CortexMotion processing regions apart from V5+/MT+ are still relatively poorly understood. Here, we used functional magnetic resonance imaging to perform a detailed functional analysis of the recently described cingulate sulcus visual area (CSv) in the dorsal posterior cingulate cortex. We used distinct types of visual motion stimuli to compare CSv with V5/MT and MST, including a visual pursuit paradigm. Both V5/MT and MST preferred 3D flow over 2D planar motion, responded less yet substantially to random motion, had a strong preference for contralateral versus ipsilateral stimulation, and responded nearly equally to contralateral and to full-field stimuli. In contrast, CSv had a pronounced preference to 2D planar motion over 3D flow, did not respond to random motion, had a weak and nonsignificant lateralization that was significantly smaller than that of MST, and strongly preferred full-field over contralateral stimuli. In addition, CSv had a better capability to integrate eye movements with retinal motion compared with V5/MT and MST. CSv thus differs from V5+/MT+ by its unique preference to full-field, coherent, and planar motion cues. These results place CSv in a good position to process visual cues related to self-induced motion, in particular those associated to eye or lateral head movements.nonotspecifiedhttp://www.cyberneum.de/published11Visual Motion Responses in the Posterior Cingulate Sulcus: A Comparison to V5/MT and MST15017154221501715421HongBS20127AHongHHBülthoffHISonSeoul, South Korea2012-04-0035535627th ICROS Annual Conference (ICROS 2012)In this paper, we propose a multimodal (i.e., visual and force) feedback method to enhance a human operator’s situational awareness in multi-robot teleoperation using only local information of the robots. The proposed method, then, are evaluated via a psychophysical experiment. The visual feedback is developed with local (real) views captured by an on-board camera in each slave robot and a global (fabricated) one regarding the formation of all slave robots as well as directions of the cameras. Position/velocity information of the slave robots is transmitted to the operator as the force feedback. We anticipate to find the benefit of the proposed multimodal feedback in multi-robot teleoperation and to let us design an enhanced multimodal feedback with this finding.nonotspecifiedhttp://www.cyberneum.de/published1Experimental Design for the Evaluation of a Multimodal Feedback in Multi-Robot Teleoperation1501715422Bulthoff2012_210HHBülthoffBulthoff201210HHBülthoffFischerBLB20123EFischerHHBülthoffNKLogothetisABartels2012-03-0067312281240NeuronLittle is known about mechanisms mediating a stable perception of the world during pursuit eye movements. Here, we used fMRI to determine to what extent human motion-responsive areas integrate planar retinal motion with nonretinal eye movement signals in order to discard self-induced planar retinal motion and to respond to objective (“real”) motion. In contrast to other areas, V3A lacked responses to self-induced planar retinal motion but responded strongly to head-centered motion, even when retinally canceled by pursuit. This indicates a near-complete multimodal integration of visual with nonvisual planar motion signals in V3A. V3A could be mapped selectively and robustly in every single subject on this basis. V6 also reported head-centered planar motion, even when 3D flow was added to it, but was suppressed by retinal planar motion. These findings suggest a dominant contribution of human areas V3A and V6 to head-centered motion perception and to perceptual stability during eye movements.nonotspecifiedhttp://www.cyberneum.de/published12Human Areas V3A and V6 Compensate for Self-Induced Planar Visual Motion15017154221501715421MachullaDFE20113TKMachullaMDi LucaEFröhlichMOErnst2012-03-0012178997Experimental Brain ResearchRecent studies show that repeated exposure to an asynchrony between auditory and visual stimuli shifts the point of subjective simultaneity. Usually, the measurement stimuli used to assess this aftereffect are interleaved with short re-exposures to the asynchrony. In a first experiment, we show that the aftereffect declines during measurement in spite of the use of re-exposures. In a second experiment, we investigate whether the observed decline is either due to a dissipation of the aftereffect with the passage of time, or the result of using measurement stimuli with a distribution of asynchronies different from the exposure stimulus. To this end, we introduced a delay before measuring the aftereffects and we compared the magnitude of the aftereffect with and without delay. We find that the aftereffect does not dissipate during the delay but instead is stored until new sensory information in the form of measurement stimuli is presented as counterevidence (i.e., stimuli with an asynchrony that differs from the one used during exposure).nonotspecifiedhttp://www.cyberneum.de/published8Multisensory simultaneity recalibration: storage of the aftereffect in the absence of counterevidence15017188241501715422KaulardCBW20123KKaulardDWCunninghamHHBülthoffCWallraven2012-03-0037118PLoS OneThe ability to communicate is one of the core aspects of human life. For this, we use not only verbal but also nonverbal signals of remarkable complexity. Among the latter, facial expressions belong to the most important information channels. Despite the large variety of facial expressions we use in daily life, research on facial expressions has so far mostly focused on the emotional aspect. Consequently, most databases of facial expressions available to the research community also include only emotional expressions, neglecting the largely unexplored aspect of conversational expressions. To fill this gap, we present the MPI facial expression database, which contains a large variety of natural emotional and conversational expressions. The database contains 55 different facial expressions performed by 19 German participants. Expressions were elicited with the help of a method-acting protocol, which guarantees both well-defined and natural facial expressions. The method-acting protocol was based on every-day scenarios, which are used to define the necessary context information for each expression. All facial expressions are available in three repetitions, in two intensities, as well as from three different camera angles. A detailed frame annotation is provided, from which a dynamic and a static version of the database have been created. In addition to describing the database in detail, we also present the results of an experiment with two conditions that serve to validate the context scenarios as well as the naturalness and recognizability of the video sequences. Our results provide clear evidence that conversational expressions can be recognized surprisingly well from visual information alone. The MPI facial expression database will enable researchers from different research fields (including the perceptual and cognitive sciences, but also affective computing, as well as computer vision) to investigate the processing of a wider range of natural facial expressions.nonotspecifiedhttp://www.cyberneum.de/published17The MPI Facial Expression Database: A Validated Database of Emotional and Conversational Facial Expressions1501715422Breidt2012_215MBreidt2012-03-00nonotspecifiedpublishedDatenbasierte Gesichtsanimation1501715422Lachele201214JLächele2012-03-00nonotspecifiedpublishedDevelopment of a Real-Time Simulation Environment for multiple Robot Systemsdiplom1501715422RobuffoGiordano2012_410PRobuffo GiordanoMeilinger201210TMeilingerBulthoff2012_1410IBülthoffFrankensteinMBM20113JFrankensteinBJMohlerHHBülthoffTMeilinger2012-02-00223120125Psychological ScienceWe examined how a highly familiar environmental space—one’s city of residence—is represented in memory. Twenty-six participants faced a photo-realistic virtual model of their hometown and completed a task in which they pointed to familiar target locations from various orientations. Each participant’s performance was most accurate when he or she was facing north, and errors increased as participants’ deviation from a north-facing orientation increased. Pointing errors and latencies were not related to the distance between participants’ initial locations and the target locations. Our results are inconsistent with accounts of orientation-free memory and with theories assuming that the storage of spatial knowledge depends on local reference frames. Although participants recognized familiar local views in their initial locations, their strategy for pointing relied on a single, north-oriented reference frame that was likely acquired from maps rather than experience from daily exploration. Even though participants had spent significantly more time navigating the city than looking at maps, their pointing behavior seemed to rely on a north-oriented mental map.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/Psychol-Sci-2012-Frankenstein.pdfpublished5Is the Map in Our Head Oriented North?1501715422AlexandrovaRBTKBM20127IVAlexandrovaMRallMBreidtGTulliusCKloosHHBülthoffBJMohlerNewport Beach, CA, USA2012-02-00162219th Medicine Meets Virtual Reality Conference (MMVR 2012)The aim of this work is to increase the effectiveness of real world medical training simulations by helping trainees gain a better understanding of the importance of communication and teamwork. Therefore we develop an online application which can be used together with real world simulations to improve training. To produce the online application we reconstructed two real world scenarios (one with students and one with practitioners) in an immersive virtual environment. Our application enables the trainees to view the scenario from different perspectives or to freely explore the environment. We aim to integrate it into the medical student curriculum at the University of Tübingen.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/MMVR-2012-Alexandrova.pdfpublished6Enhancing Medical Communication Training Using Motion Capture, Perspective Taking and Virtual Reality1501715422RobuffoGiordano2012_510PRobuffo GiordanoGaissertW2011_23NGaissertCWallraven2012-01-001216123134Experimental Brain ResearchAlthough the hands are the most important tool for humans to manipulate objects, only little is known about haptic processing of natural objects. Here, we selected a unique set of natural objects, namely seashells, which vary along a variety of object features, while others are shared across all stimuli. To correctly interact with objects, they have to be identified or categorized. For both processes, measuring similarities between objects is crucial. Our goal is to better understand the haptic similarity percept by comparing it to the visual similarity percept. First, direct similarity measures were analyzed using multidimensional scaling techniques to visualize the perceptual spaces of both modalities. We find that the visual and the haptic modality form almost identical perceptual spaces. Next, we performed three different categorization tasks. All tasks exhibit a highly accurate processing of complex shapes of the haptic modality. Moreover, we find that objects grouped into the same category form regions within the perceptual space. Hence, in both modalities, perceived similarity constitutes the basis for categorizing objects. Moreover, both modalities focus on shape to form categories. Taken together, our results lead to the assumption that the same cognitive processes link haptic and visual similarity perception and the resulting categorization behavior.nonotspecifiedhttp://www.cyberneum.de/published11Categorizing natural objects: a comparison of the visual and the haptic modalities1501715422DurhamFB20113JWDurhamAFranchiFBullo2012-01-001328195Autonomous RobotsThis paper addresses a visibility-based pursuit-evasion problem in which a team of mobile robots with limited sensing and communication capabilities must coordinate to detect any evaders in an unknown, multiply-connected planar environment. Our distributed algorithm to guarantee evader detection is built around maintaining complete coverage of the frontier between cleared and contaminated regions while expanding the cleared region. We detail a novel distributed method for storing and updating this frontier without building a map of the environment or requiring global localization. We demonstrate the functionality of the algorithm through simulations in realistic environments and through hardware experiments. We also compare Monte Carlo results for our algorithm to the theoretical optimum area cleared as a function of the number of robots available.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/2011c-DurFraBul-preprint.pdfpublished14Distributed pursuit-evasion without mapping or global localization via local frontiers150171542249583TMeilingerGFranzHHBülthoff2012-01-001394862Environment and Planning B: Planning and DesignThis paper addresses the interactions between human wayfinding performance, the mental representation of routes, and the geometrical layout of path intersections. The conclusions of this paper are based on the results of a virtual reality empirical experiment. The study consisted of a route-learning and reproduction task and two choice reaction tasks measuring the acquired knowledge of route decision points. In order to relate the recorded behaviour to the geometry of the environment, a specific adaptation of an isovist-based spatial analysis that accounts for directional bias in human spatial perception and representation was developed. The analyses applied provided conclusive evidence of correspondences between the geometrical properties of environments as captured by isovists and their mental representations.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2012/Environment-Planning-B-2012-Meilinger.pdfpublished14From Isovists via Mental Representations to Behaviour: First Steps Toward Closing the Causal Chain1501715422DopjansBW20123LDopjansHHBülthoffCWallraven2012-01-001:612114Journal of VisionEven though we can recognize faces by touch surprisingly well, haptic face recognition performance is still worse than for visual exploration. One possibility for this performance difference might be due to different encoding strategies in the two modalities, namely, holistic encoding in vision versus serial encoding in haptics. Here, we tested this hypothesis by promoting serial encoding in vision, using a novel, gaze-restricted display that limited the effective field of view in vision to resemble that of haptic exploration. First, we compared haptic with gaze-restricted and unrestricted visual face recognition. Second, we used the face inversion paradigm to assess how encoding differences might affect processing strategies (featural vs. holistic). By promoting serial encoding in vision, we found equal face recognition performance in vision and haptics with a clear switch from holistic to featural processing, suggesting that performance differences in visual and haptic face recognition are due to modality-specific encoding strategies.nonotspecifiedhttp://www.cyberneum.de/published13Serial exploration of faces: Comparing vision and touch1501715422CamposB20112JLCamposHHBülthoffCRC PressBoca Raton, FL, USA2012-01-00603628The neural bases of multisensory processesThis chapter begins by a brief description of some of the different types of simulation tools and techniques that are being used to study self-motion perception, along with some of the advantages and disadvantages of the different interfaces. Subsequently, some of the current empirical work investigating multisensory self-motion perception using these technologies will be summarized, focusing mainly on visual, proprioceptive, and vestibular influences during full-body self-motion through space. Finally, the implications of this research for several applied areas will be briefly described.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/Campos-Buelthoff-MultisensorySelfMotion.pdfpublished25Multimodal Integration during Self-Motion in Virtual Reality1501715422NestiBMB20127ANestiMBarnett-CowanPMacNeilageHHBülthoffZürich, Switzerland2012-01-0022nd Okulomotoriktreffen Zürich-Münchennonotspecifiedhttp://www.cyberneum.de/published0Differential Thresholds for Vertical Motion1501715422SoykaRBB20127FSoykaPRobuffo GiordanoMBarnett-CowanHHBülthoffZürich, Switzerland2012-01-0022nd Okulomotoriktreffen Zürich-Münchennonotspecifiedhttp://www.cyberneum.de/published0Reaction Times for Self-Motion Detection1501715422Nieuwenhuizen2012_31FMNieuwenhuizenLogos VerlagBerlin, Germany2012-00-00Flight simulators provide an effective, efficient, and safe environment for practising flight-critical manoeuvres without requiring a real aircraft. In general, high-performance full flight simulators are used for training tasks that require simulator motion, although low-cost motion systems have been proposed for certain training tasks that only require limited motion cues. These systems have shorter stroke actuators, lower bandwidth, and higher motion noise. The influence of these characteristics on pilot perception and control behaviour is unknown. In this thesis, this is investigated by simulating a model of a simulator with limited capabilities on a high-end simulator. The simulator limitations, which consist of a platform filter, time delay, and noise characteristics, can then be removed one by one and their effect on control behaviour studied in isolation. Pilot perception and control behaviour was identified in an experimental closed-loop control task. The time delay and noise characteristics of the simulators did not have an effect on pilot behaviour. However, it was found that the bandwidth of the motion system had a significant effect on performance and control behaviour. Results indicate that the motion cues were barely used at all in conditions with a low bandwidth, and that participants relied on the visual cues to perform the control task. The approach used in this thesis provided valuable insight into changes in pilot response dynamics that form the basis of observed changes in performance. The results demonstrated that simulator motion cues must be considered carefully in piloted control tasks in simulators and that measured results depend on simulator characteristics as pilots adapt their control behaviour to the available cues.Delft, Technische Univ., Diss., 2012nonotspecifiedhttp://www.cyberneum.de/published266Changes in Pilot Control Behaviour across Stewart Platform Motion Systems1501715422Breidt20121MBreidtLogos VerlagBerlin, Germany2012-00-00Die Erzeugung realistischer 3D-Computeranimationen von Gesichtern ist auf Grund der hohen Bedeutung des menschlichen Gesichts für eine Vielzahl von Anwendungsbereichen von Interesse. Neben virtuellen Schauspielern in der Film- und Computerspiele-Industrie oder Online-Avataren verlangt auch die experimentelle Untersuchung der menschlichen Wahrnehmung von Gesichtern nach effizienten Lösungen zur Erstellung von Gesichtsanimationen. Insbesondere die experimentelle Verwendung motiviert den in dieser Arbeit vertretenen datenbasierten Ansatz, der möglichst ohne die in der Industrie übliche kreativ-handwerkliche Gestaltung der Gesichtsdaten auskommen will.
Die Arbeit beschreibt, wie Messdaten realer Gesichter in Form von Motion Capture sowie 3D- bzw. 4D-Scans für diese Aufgabe eingesetzt werden können. Ausgehend von der Grundannahme der Darstellbarkeit eines Gesichts und dessen Bewegungen als Linearkombination werden Möglichkeiten der Gewinnung und Nutzung solcher Daten aufgezeigt:
Der erste Teil kombiniert statische Oberflächenmessungen des Gesichts in Form von räumlich hoch aufgelösten 3D-Scans mit den zeitlich hoch aufgelösten, markerbasierten Bewegungsdaten eines Motion-Capture-Systems. Hierzu werden die gemessenen Bewegungen durch eine semantische Parametrisierung auf Basis des Facial Action Coding Systems (FACS) dargestellt. Dies erlaubt nicht nur die identitätsunabhängige Übertragung der Bewegung auf ein beliebiges Gesicht, sondern auch eine kompakte und gleichzeitig interpretierbare Beschreibung der Bewegung.
Die zweite Hälfte der Arbeit baut auf neuen Messverfahren auf, die eine detaillierte 3D-Aufnahme des zeitlichen und räumlichen Verlaufs komplexer Gesichtsbewegungen in einem einzigen Aufnahmevorgang als 4D-Scan ermöglichen. Um solche Daten jedoch systematisch einsetzen und verändern zu können, werden Methoden zur Herstellung einer Korrespondenz zwischen den einzelnen Zeitschritten der Aufnahme benötigt. Hierzu werden sowohl ein modellfreies Verfahren als auch ein modellbasiertes Verfahren zur Rekonstruktion von Gesichtsbewegungen vorgestellt. Mit Hilfe des modellbasierten Ansatzes wird zudem gezeigt, wie stark verrauschte Daten echtzeitfähiger Tiefensensoren rekonstruiert werden können. Schließlich wird die modellbasierten Bewegungsanalyse dazu verwendet, aus Aufnahmen komplexer Gesichtsbewegungen FACS-Aktivierungen zu gewinnen und damit ein individuelles Gesichtsmodell zu berechnen, das interpretierbare Parameter besitzt.Tübingen, Univ., Diss., 2012nonotspecifiedhttp://www.cyberneum.de/published175Datenbasierte Gesichtsanimation15017154226567WReadingerAChatziastrosDCunninghamHHBülthoffJECuttingBrisbane, Australia2012-00-003213269th International Conference Vision in Vehicles (VIV 2001)Instructions given to novices learning certain tasks of applied navigation often suggest that gazedirection (?line of sight?) should preview the path the operator desires to take (e.g., Bondurant & Blakemore, 1998; Motorcycle Safety Foundation, 1992; Morris, 1990), presumably because looking behavior can ultimately affect steering control through hand, arm, or leg movements that could lead to undesired path deviations. Here, we control participants? gaze-direction while driving an automobile in virtual reality, and find that gaze-eccentricity has a large, systematic effect on steering and lane-position. Moreover, even when head-position and postural effects of the driver are controlled, there remains a significant bias to drive in the direction of fixation, indicating the existence of a perceptual, and not merely motor, phenomenon.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/VIV-2001-Readinger.pdfpublished5Gaze-direction and steering effects while driving150171542240777PPrettoAChatziastrosDublin, Ireland2012-00-0020721611th International Conference on Vision in Vehicles (VIV 2006)nonotspecifiedhttp://www.cyberneum.de/published9The role of scene contrast and optic flow on driving speed15017154226477AChatziastrosGMWallisHHBülthoffBoston, MA, USA2012-00-002652768th International Conference on Vision in Vehicles (VIV 1999)In the present experiment we investigated the importance of velocity information during a lane-centering task between the walls of a simulated tunnel. We varied both simulated velocity and the spatial frequency content of the walls' surfaces, in order to address the influence of each parameter on steering performance. Further, this performance was compared to the effectiveness of lateral control using lane border information. We found that drivers used both velocity and spatial frequency information to maintain a centered position on a path, and that the presence of lane borders improved accuracy. The results suggest that multiple sources of visual information, rather than mere demarcating lines, are used for lateral control on a straight path.nonotspecifiedhttp://www.cyberneum.de/published11The use of splay angle and optical flow in steering a central path1501715422Spica201214RSpica2012-00-00nonotspecifiedpublishedPlanning and control of aerial grasping with a quadrotor UAVmaster1501715422RobuffoGiordano2011_410PRobuffo GiordanoMeilinger2011_310TMeilingerMeilinger201110TMeilingerBulthoff2011_1110HHBülthoffIsenbergC20113TIsenbergDCunningham2011-12-008302457–2458Computer Graphics Forumnonotspecifiedhttp://www.cyberneum.de/published-2457Computational Aesthetics 2011 in Vancouver, Canada, August 5–7, 2011, Sponsored by Eurographics, in Collaboration with ACM SIGGRAPH1501715422FlemingHB20113RWFlemingDHoltmann-RiceHHBülthoff2011-12-00511082043820443Proceedings of the National Academy of Sciences of the United States of AmericaOne of the main functions of vision is to estimate the 3D shape of objects in our environment. Many different visual cues, such as stereopsis, motion parallax, and shading, are thought to be involved. One important cue that remains poorly understood comes from surface texture markings. When a textured surface is slanted in 3D relative to the observer, the surface patterns appear compressed in the retinal image, providing potentially important information about 3D shape. What is not known, however, is how the brain actually measures this information from the retinal image. Here, we explain how the key information could be extracted by populations of cells tuned to different orientations and spatial frequencies, like those found in the primary visual cortex. To test this theory, we created stimuli that selectively stimulate such cell populations, by “smearing” (filtering) images of 2D random noise into specific oriented patterns. We find that the resulting patterns appear vividly 3D, and that increasing the strength of the orientation signals progressively increases the sense of 3D shape, even though the filtering we apply is physically inconsistent with what would occur with a real object. This finding suggests we have isolated key mechanisms used by the brain to estimate shape from texture. Crucially, we also find that adapting the visual system's orientation detectors to orthogonal patterns causes unoriented random noise to look like a specific 3D shape. Together these findings demonstrate a crucial role of orientation detectors in the perception of 3D shape.nonotspecifiedhttp://www.cyberneum.de/published5Estimation of 3D shape from image orientations1501715422LeeN2011_23HLLeeUNoppeney2011-12-0051108E1441E1450Proceedings of the National Academy of Sciences of the United States of AmericaPracticing a musical instrument is a rich multisensory experience involving the integration of visual, auditory, and tactile inputs with motor responses. This combined psychophysics–fMRI study used the musician's brain to investigate how sensory-motor experience molds temporal binding of auditory and visual signals. Behaviorally, musicians exhibited a narrower temporal integration window than nonmusicians for music but not for speech. At the neural level, musicians showed increased audiovisual asynchrony responses and effective connectivity selectively for music in a superior temporal sulcus-premotor-cerebellar circuitry. Critically, the premotor asynchrony effects predicted musicians’ perceptual sensitivity to audiovisual asynchrony. Our results suggest that piano practicing fine tunes an internal forward model mapping from action plans of piano playing onto visible finger movements and sounds. This internal forward model furnishes more precise estimates of the relative audiovisual timings and hence, stronger prediction error signals specifically for asynchronous music in a premotor-cerebellar circuitry. Our findings show intimate links between action production and audiovisual temporal binding in perception.nonotspecifiedhttp://www.cyberneum.de/published0Long-term music training tunes how the brain temporally binds signals from multiple senses15017188261501715422ChillerGlausSHKK20113SDChiller-GlausASchwaningerFHoferMKleinerBKnappmeyer2011-12-00470233240Swiss Journal of PsychologyThis paper investigates whether the greater accuracy of emotion identification for dynamic versus static expressions, as noted in previous research, can be explained through heightened levels of either component or configural processing. Using a paradigm by Young, Hellawell, and Hay (1987), we tested recognition performance of aligned and misaligned composite faces with six basic emotions (happiness, fear, disgust, surprise, anger, sadness). Stimuli were created using 3D computer graphics and were shown as static peak expressions (static condition) and 7 s video sequences (dynamic condition). The results revealed that, overall, moving stimuli were better recognized than static faces, although no interaction between motion and other factors was found. For happiness, sadness, and surprise, misaligned composites were better recognized than aligned composites, suggesting that aligned composites fuse to form a single expression, while the two halves of misaligned composites are perceived as two separate emotions. For anger, disgust, and fear, this was not the case. These results indicate that emotions are perceived on the basis of both configural and component-based information, with specific activation patterns for separate emotions, and that motion has a quality of its own and does not increase configural or component-based recognition separately.nonotspecifiedhttp://www.cyberneum.de/published7Recognition of emotion in moving and static composite faces1501715422FranchiRB20117AFranchiHHBülthoffPRobuffo GiordanoOrlando, FL, USA2011-12-003559356550th IEEE Conference on Decision and Control and European Control Conference (CDC - ECC 2011)For several applications like data collection, surveillance, search and rescue and exploration of wide areas, the use of a group of simple robots rather than a single complex robot has proven to be very effective and promising, and the problem of coordinating a group of agents has received a lot of attention over the last years. In this paper, we consider the challenge of establishing a bilateral force-feedback teleoperation channel between a human operator (the master side) and a remote multi-robot system (the slave side) where a special agent, the leader, is selected and directly controlled by the master. In particular, we study the problem of distributed online optimal leader selection, i.e., how to choose, and possibly change, the leader online in order to maximize some suitable criteria related to the tracking performance of the whole group w.r.t. the master commands. Human/hardware-in-the-loop simulation results with a group of UAVs support the theoretical claims of the paper.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/CDC-ECC-2011-Franchi.pdfpublished6Distributed Online Leader Selection in the Bilateral Teleoperation of Multiple UAVs1501715422SteinickeWLM20117FSteinickeMCWhittonALécuyerBMohlerHong Kong, China2011-12-0018: 134th ACM SIGGRAPH Conference and Exhibition on Computer Graphics and Interactive Techniques in Asia ( (SIGGRAPH Asia 2011)In recent years many advances have enabled users to naturally navigate large-scale graphical worlds. The entertainment industry is increasingly providing visual and body-based cues to users to increase the natural feel of their navigational experience. So far, however, none of the existing solutions fully support the most natural locomotion through virtual worlds. Techniques and technologies which have the advantage of insights into human perceptual sensitivity thus have to be considered. In this context, by far the most natural way to move through the real world is via a full body experience where we receive sensory stimulation to all of our senses, i.e. when walking, running, biking or driving. With some exciting technological advances, people are now beginning to get this same full body sensory experience when navigating computer-generated, three-dimensional environments. Enabling an active and dynamic ability to navigate large-scale virtual scenes is of great interest for many 3D applications demanding locomotion, such as video games, edutainment, simulation, rehabilitation, military, tourism or architecture. Today it is still mostly impossible to freely move through computer generated environments in exactly the same way as the real world. Unnatural and artificial approaches are instead applied, providing only the visual sensation of self-motion. Computer graphics environments were initially restricted to visual displays combined with interaction devices - for example the joystick or mouse - providing often unnatural inputs to generate self-motion. Today, more and more interaction devices like Nintendo Wii, Microsoft Kinect or Sony EyeToy enable intuitive and natural interaction. In this context many research groups are investigating natural, multimodal methods of generating self-motion in virtual worlds based on such consumer hardware.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/ACM-Siggraph-Asia-2011-Steinick.pdfpublished-15Perceptually inspired methods for naturally navigating virtual worlds1501715422RobuffoGiordano2011_310PRobuffo GiordanoFranchi2011_310AFranchiLeoN2011_210FLeoUNoppeneyChandrasekaranLG20117CChandrasekaranLLemusAAGhazanfarWashinton, DC, USA2011-11-11Tucker-Davis Symposium on Advances and Perspectives in Auditory Neurophysiology (APAN 2011)nonotspecifiedhttp://www.cyberneum.de/published0Dynamic faces speed up vocal processing in the auditory cortex of behaving monkeys15017154221501715421BulthoffN2011_210HHBülthoffFMNieuwenhuizenChuang2011_410LChuangSoumanRSFTUDBE20113JLSoumanPRobuffo GiordanoMSchwaigerIFrissenTThümmelHUlbrichADe LucaHHBülthoffMErnst2011-11-004:258122ACM Transactions on Applied PerceptionDespite many recent developments in Virtual Reality, an effective locomotion interface which allows for normal walking through large virtual environments was still lacking until recently. Here, we describe the new CyberWalk omnidirectional treadmill system, which makes it possible for users to walk endlessly in any direction, while never leaving the confines of the limited walking surface. The treadmill system improves on previous designs, both in its mechanical features and in the control system employed to keep users close to the centre of the treadmill. As a result, users are able to start walking, vary their walking speed and direction, and stop walking like they would on a normal, stationary surface. The treadmill system was validated in two experiments, in which both the walking behaviour and the performance in a basic spatial updating task were compared to that during normal overground walking. The results suggest that walking on the CyberWalk treadmill is very close to normal walking, especially after some initial familiarization. Moreover, we did not find a detrimental effect of treadmill walking in the spatial updating task. The CyberWalk system constitutes a significant step forward to bringing the real world into the laboratory or workplace.nonotspecifiedhttp://www.cyberneum.de/published21CyberWalk: Enabling unconstrained omnidirectional walking through virtual environments15017154221501718824ArmannJCR20113RArmannLJefferyAJCalderGRhodes2011-11-0013:911114Journal of VisionModels of face perception often adopt a framework in which faces are represented as points or vectors in a multidimensional space, relative to the average face that serves as a norm for encoding. Since faces are very similar in their configuration and share many visual properties, they could be encoded in one common space against one norm. However, certain face properties may result in grouping and “subclassification” of similar faces. We studied the processing of faces of different races, using high-level aftereffects, where exposure to one face systematically distorts the perception of a subsequently viewed face toward the “opposite” identity in face space. We measured identity aftereffects for adapt–test pairs that were opposite relative to race-specific (Asian and Caucasian) averages and pairs that were opposite relative to a “generic” average (both races morphed together). Aftereffects were larger for race-specific compared to mixed-race adapt–test pairs. These results suggest that race-specific norms are used to code identity because aftereffects are generally larger for adapt–test pairs drawn from trajectories passing through the norm (opposite pairs) than for those that do not. We also found that identification thresholds were lower when targets were distributed around race-specific averages than around the mixed-race average, suggesting that norm-based face encoding may play a functional role in facilitating identity discrimination.nonotspecifiedhttp://www.cyberneum.de/published13Race-specific norms for coding face identity and a functional role for norms1501715422BrowatzkiFGBW20117BBrowatzkiJFischerBGrafHHBülthoffCWallravenBarcelona, Spain2011-11-00118911951st ICCV Workshop on Consumer Depth Cameras in Computer Vision (CD4CV2011)Categorization of objects solely based on shape and appearance is still a largely unresolved issue. With the advent of new sensor technologies, such as consumer-level range sensors, new possibilities for shape processing have become available for a range of new application domains. In the first part of this paper, we introduce a novel, large dataset containing 18 categories of objects found in typical household and office environments-we envision this dataset to be useful in many applications ranging from robotics to computer vision. The second part of the paper presents computational experiments on object categorization with classifiers exploiting both two-dimensional and three-dimensional information. We evaluate categorization performance for both modalities in separate and combined representations and demonstrate the advantages of using range data for object and shape processing skills.nonotspecifiedhttp://www.cyberneum.de/published6Going into depth: Evaluating 2D and 3D cues for object classification on a new, large-scale object dataset1501715422NieuwenhuizenJPWPFSZFBSMSDGHB20117FMNieuwenhuizenMJumpPPerfectMDWhiteGDPadfieldDFloreanoFSchillJ-CZuffereyPFuaSBouabdallahRSiegwartSMeyerJSchipplMDeckerBGurskyMHöfingerHHBülthoffFrankfurt a.M., Germany2011-11-00183rd International HELI World Conference 2011 "Helicopter Technologies and Operations" (HeliWorld 2011)Current road transportation systems throughout the European Union suffer from severe congestion problems. A solution can be to move towards a Personal Aerial Transportation System, in which vehicles would also have vertical space at their disposal. In the myCopter project, funded by the European Union under the 7th Framework Programme, the viability of such a system will be investigated. It is argued that this should be done by taking into account the required operational infrastructure, instead of starting with the design of a vehicle. By investigating human-machine
interfaces and training, automation technologies, and socio-economic impact, the myCopter project aims to provide a basis for a transportation system based on Personal Aerial Vehicles. In this paper, an outline of the project is given. Early research results are detailed and provide a basis for the remainder of the project.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/HeliWorld-2011-Nieuwenhuizen.pdfpublished7myCopter: Enabling Technologies for Personal Aerial
Transportation Systems1501715422SchindlerKB20117ASchindlerMKleinerABartelsWashington, DC, USA2011-11-0041st Annual Meeting of the Society for Neuroscience (Neuroscience 2011)In our subjective experience, there is a tight link between covert visual attention and ego-centric spatial attention. One key difference is that the latter can extend beyond the visual field, providing us with an accurate mental representation of an object’s location relative to our body position. A neural link between visual and ego-centric spatial attention is suggested by lesions in parietal cortex, that lead not only to deficits in covert visual attention, but frequently also to a disorder of ego-centric spatial awareness, known as hemi-spatial neglect. While parietal involvement in covert visual spatial attention has been much studied, relatively little is known about mental representations of the unseen space around us.
In the present study we examined whether also unseen spatial locations beyond the visual field are represented in parietal activity, and how they are related to retinotopic representations. We employed a novel virtual reality (VR) paradigm during functional magnetic resonance imaging (fMRI), whereby observers were prompted to draw their spatial attention to the position of one of eight possible objects located around them in an octagonal room. By changing the observers’ facing direction every few trials, the egocentric location of objects was disentangled from their absolute position and from the objects’ identity. Thus, mental representations of egocentric space surrounding the observer were sampled eight-fold.
De-coding results of a multivariate pattern analysis classifier (MVPA), but not univariate results, showed that egocentric spatial directions were specifically represented in parietal cortex. These representations overlapped only partly with visually driven retinotopic activity.
Our results thus show that parietal cortex codes not only for retinotopic and visually accessible space, but also for egocentric locations of the three-dimensional space surrounding us, including unseen space.nonotspecifiedhttp://www.cyberneum.de/published0Decoding egocentric space in human posterior parietal cortex using fMRI15017154211501715422PapeWSBM20117A-APapeTWolbersJSchultzHHBülthoffTMeilingerWashington, DC, USA2011-11-0041st Annual Meeting of the Society for Neuroscience (Neuroscience 2011)Grid cells in entorhinal cortex of freely moving rodents were proposed to provide a universal metric of space. They tile the environment into a six-fold symmetric pattern with a particular orientation relative to the environment. The six-fold rotational symmetry of grid patterns can be used to predict a macroscopic signal to functional magnetic resonance imaging (fMRI) in humans [Doeller et al, 2010, Nature]. During hippocampal remapping, grid pattern orientations in rats also change. The purpose of the present study is to examine whether orientation changes (i.e., remapping) can also be found in humans. Participants learned object locations within a virtual room (see Figure 1 left side) and retrieved locations from different start locations during two scanning sessions. They then navigated into an adjacent room and repeated the procedure. We extracted grid orientations from odd trials, and predicted the BOLD response in even trials as a function of the deviation between running direction and the estimated grid orientation for each session. This prediction was significant for the right entorhinal cortex, replicating earlier findings. In 80% of the cases grid cell orientations significantly differed between sessions both within a room and between rooms (see Figure 1 right side). Switching off the virtual environment between sessions for about one minute was seemingly sufficient for that. For male, but not for female participants, grid cell orientation was clustered around the random view of the room experienced at session start. Data suggests that human grid cell orientations can be rather flexible which might be due to the virtuality of the experience. Grid cell orientation might at least for male participants be related to the initial view of an environment.nonotspecifiedhttp://www.cyberneum.de/published0Grid cell remapping in humans1501715422BulthoffN2011_3HHBülthoffH-GNusseck2011-10-25The invention relates to an image processing device (1, 48, 51) including: several image signal inputs (2-9) for receiving a respective image input signal, the signals being unsynchronized; at least one image signal output (23-26) for emitting at least one image output signal; a combiner (22) for combining the different image input signals to form the image output signal; several synchronizers (14-21), which are respectively connected downstream of the image signal inputs (2-9) and which synchronize the unsynchronized image input signals; and several distorters or rectifiers for distorting or rectifying the individual image input signals before they are combined to form the image output signal. According to the invention, the distorters or rectifiers are formed by the individual synchronizers (14-21) and the image input signals are distorted or rectified independently of one another by one or more synchronizers (14-21). The invention also relates to an associated operating method.nonotspecifiedhttp://www.cyberneum.de/publishedImage processing device and associated operating method [Bildverarbeitungseinrichtung und entsprechendes Betriebsverfahren]1501715422SoykadBGB20117FSoykaKNde WinkelMBarnett-CowanEGroenHHBülthoffFukuoka, Japan2011-10-1885512th International Multisensory Research Forum (IMRF 2011)Do humans integrate visual and vestibular information in a statistically optimal fashion when discriminating rotational self-motion stimuli? Recent studies are inconclusive as to whether such integration occurs when discriminating heading direction.
In the present study eight participants were consecutively rotated twice (2s sinusoidal acceleration) on a chair about an earth-vertical axis in vestibular-only, visual-only and visual-vestibular trials. The visual stimulus was a video of a moving stripe pattern, synchronized with the inertial motion. Peak acceleration of the reference stimulus was varied and participants reported which rotation was perceived as faster. Just-noticeable differences (JND) were estimated by fitting psychometric functions.
The visual-vestibular JND measurements are too high compared to the predictions based on the unimodal JND estimates and there is no JND reduction between visual-vestibular and visual-alone estimates. These findings may be explained by visual capture. Alternatively, the visual precision may not be equal between visual-vestibular and visual-alone conditions, since it has been shown that visual motion sensitivity is reduced during inertial self-motion. Therefore, measuring visual-alone JNDs with an underlying uncorrelated inertial motion might yield higher visual-alone JNDs compared to the stationary measurement. Theoretical calculations show that higher visual-alone JNDs would result in predictions consistent with the JND measurements for the visual-vestibular condition.nonotspecifiedhttp://www.cyberneum.de/published-855Integration of visual and vestibular information used to discriminate rotational self-motion1501715422GaissertWvBW201110NGaissertSWaterkampLvan DamHHBülthoffCWallravenVolkovaMLAB20117EVolkovaBMohlerSLinkenaugerIAlexandrovaHHBülthoffFukuoka, Japan2011-10-1777412th International Multisensory Research Forum (IMRF 2011)Recent technology provides us with realistic looking virtual characters. Motion capture and elaborate mathematical models supply data for natural looking, controllable facial and bodily animations. With the help of computational linguistics and artificial intelligence, we can automatically assign emotional categories to appropriate stretches of text for a simulation of those social scenarios where verbal communication is important.
All this makes virtual characters a valuable tool for creation of versatile stimuli for research on the integration of emotion information from different modalities.
We conducted an audio-visual experiment to investigate the differential contributions of emotional speech and facial expressions on emotion identification. We used recorded and synthesized speech as well as dynamic virtual faces, all enhanced for seven emotional categories. The participants were asked to recognize the prevalent emotion of paired faces and audio.
Results showed that when the voice was recorded, the vocalized emotion influenced participants’ emotion identification more than the facial expression. However, when the voice was synthesized, facial expression influenced participants’ emotion identification more than vocalized emotion. Additionally, individuals did worse on a identifying either the facial expression or vocalized emotion when the voice was synthesized.
Our experimental method can help to determine how to improve synthesized emotional speech.nonotspecifiedhttp://www.cyberneum.de/published-774Contribution of Prosody in Audio-visual Integration to Emotional Perception of Virtual Characters1501715422Bulthoff2011_810HHBülthoffFranchi2011_210AFranchiLinkenaugerMP20113SALinkenaugerBJMohlerDRProffitt2011-10-00104012511253PerceptionAn embodied approach to the perception of spatial layout contends that the body is used as a ‘perceptual ruler’ with which individuals scale the perceived environmental layout. In support of this notion, previous research has shown that the perceived size of objects can be influenced by changes in the apparent size of hand. The size – weight illusion is a well known phenomenon, which occurs when people lift two objects of equal weight but differing sizes and perceive that the larger object feels lighter. Therefore, if apparent hand size influences perceived object size, it should also influence the object’s perceived weight. In this study, we investigated this possibility by using perceived weight as a measure and found that changes in the apparent size of the hand influence objects’ perceived weight.nonotspecifiedhttp://www.cyberneum.de/published2Body-based perceptual rescaling revealed through the
size-weight illusion1501715422LeeLBJP20113CLeeSALinkenaugerJZBakdashJAJoy-GabaDRProfitt2011-10-0010614PLoS OneMany amateur athletes believe that using a professional athlete's equipment can improve their performance. Such equipment can be said to be affected with positive contagion, which refers to the belief of transference of beneficial properties between animate persons/objects to previously neutral objects. In this experiment, positive contagion was induced by telling participants in one group that a putter previously belonged to a professional golfer. The effect of positive contagion was examined for perception and performance in a golf putting task. Individuals who believed they were using the professional golfer's putter perceived the size of the golf hole to be larger than golfers without such a belief and also had better performance, sinking more putts. These results provide empirical support for anecdotes, which allege that using objects with positive contagion can improve performance, and further suggest perception can be modulated by positive contagion.nonotspecifiedhttp://www.cyberneum.de/published3Putting Like a Pro: The Role of Positive Contagion in Golf Performance and Perception1501715422DahlLBW20113CDDahlNKLogothetisHHBülthoffCWallraven2011-10-0010617PLoS OneRecognition and individuation of conspecifics by their face is essential for primate social cognition. This ability is driven by a mechanism that integrates the appearance of facial features with subtle variations in their configuration (i.e., second-order relational properties) into a holistic representation. So far, there is little evidence of whether our evolutionary ancestors show sensitivity to featural spatial relations and hence holistic processing of faces as shown in humans. Here, we directly compared macaques with humans in their sensitivity to configurally altered faces in upright and inverted orientations using a habituation paradigm and eye tracking technologies. In addition, we tested for differences in processing of conspecific faces (human faces for humans, macaque faces for macaques) and non-conspecific faces, addressing aspects of perceptual expertise. In both species, we found sensitivity to second-order relational properties for conspecific (expert) faces, when presented in upright, not in inverted, orientation. This shows that macaques possess the requirements for holistic processing, and thus show similar face processing to that of humans.nonotspecifiedhttp://www.cyberneum.de/published6Second-Order Relational Manipulations Affect Both Humans and Monkeys15017154221501715421LinkenaugerWP20113SALinkenaugerJKWittDRProffitt2011-10-0053714321441Journal of Experimental Psychology: Human Perception and PerformanceWe examined whether the apparent size of an object is scaled to the morphology of the relevant body part with which one intends to act on it. To be specific, we tested if the visually perceived size of graspable objects is scaled to the extent of apparent grasping ability for the individual. Previous research has shown that right-handed individuals perceive their right hand as larger and capable of grasping larger objects than their left. In the first 2 experiments, we found that objects looked smaller when placed in or judged relative to their right hand compared to their left. In the third experiment, we directly manipulated apparent hand size by magnifying the participants' hands. Participants perceived objects to be smaller when their hand was magnified than when their hand was unmagnified. We interpret these results as demonstrating that perceivers use the extent of their hands' grasping abilities as “perceptual rulers” to scale the apparent size of graspable objects. Furthermore, hand size manipulations did not affect the perceived size of objects too big to be grasped, which suggests that hand size is only used as a scaling mechanism when the object affords the relevant action, in this case, grasping.nonotspecifiedhttp://www.cyberneum.de/published9Taking a hands-on approach: Apparent grasping ability scales the perception of object size1501715422DoddsMB20113TJDoddsBJMohlerHHBülthoff2011-10-00106112PLoS OneBackground
When we talk to one another face-to-face, body gestures accompany our speech. Motion tracking technology enables us to include body gestures in avatar-mediated communication, by mapping one's movements onto one's own 3D avatar in real time, so the avatar is self-animated. We conducted two experiments to investigate (a) whether head-mounted display virtual reality is useful for researching the influence of body gestures in communication; and (b) whether body gestures are used to help in communicating the meaning of a word. Participants worked in pairs and played a communication game, where one person had to describe the meanings of words to the other.
Principal Findings
In experiment 1, participants used significantly more hand gestures and successfully described significantly more words when nonverbal communication was available to both participants (i.e. both describing and guessing avatars were self-animated, compared with both avatars in a static neutral pose). Participants ‘passed’ (gave up describing) significantly more words when they were talking to a static avatar (no nonverbal feedback available). In experiment 2, participants' performance was significantly worse when they were talking to an avatar with a prerecorded listening animation, compared with an avatar animated by their partners' real movements. In both experiments participants used significantly more hand gestures when they played the game in the real world.
Conclusions
Taken together, the studies show how (a) virtual reality can be used to systematically study the influence of body gestures; (b) it is important that nonverbal communication is bidirectional (real nonverbal feedback in addition to nonverbal communication from the describing participant); and (c) there are differences in the amount of body gestures that participants use with and without the head-mounted display, and we discuss possible explanations for this and ideas for future investigation.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/Dodds-TalktotheVirtualHands-PLoSOne-2011.pdfpublished11Talk to the Virtual Hands: Self-Animated Avatars Improve Communication in Head-Mounted Display Virtual Environments1501715422StreuberKSBd20113SStreuberGKnoblichNSebanzHHBülthoffSde la Rosa2011-10-002214273284Experimental Brain ResearchSocial context modulates action kinematics. Less is known about whether social context also affects the use of task relevant visual information. We tested this hypothesis by examining whether the instruction to play table tennis competitively or cooperatively affected the kind of visual cues necessary for successful table tennis performance. In two experiments, participants played table tennis in a dark room with only the ball, net, and table visible. Visual information about both players’ actions was manipulated by means of self-glowing markers. We recorded the number of successful passes for each player individually. The results showed that participants’ performance increased when their own body was rendered visible in both the cooperative and the competitive condition. However, social context modulated the importance of different sources of visual information about the other player. In the cooperative condition, seeing the other player’s racket had the largest effects on performance increase, whereas in the competitive condition, seeing the other player’s body resulted in the largest performance increase. These results suggest that social context selectively modulates the use of visual information about others’ actions in social interactions.nonotspecifiedhttp://www.cyberneum.de/published11The effect of social context on the use of visual information1501715422VenrooijMvABM20117JVenrooijMMulderMMvan PaassenDAAbbinkHHBülthoffMMulderAnchorage, AK, USA2011-10-0016701675IEEE International Conference on Systems, Man and Cybernetics (SMC 2011)Vehicle accelerations may feed through the human body, causing involuntary limb motions which may lead to involuntary control inputs. This phenomenon is called biodynamic feedthrough (BDFT). Signal cancellation is a possible way of mitigating biodynamic feedthrough. It makes use of a BDFT model to estimate the involuntary control inputs. The BDFT effects are removed by subtracting the modeled estimate of the involuntary control input from the total control signal, containing both voluntary and involuntary components. The success of signal cancellation hinges on the accuracy of the BDFT model used. In this study the potential of signal cancellation is studied by making use of a method called optimal signal cancellation. Here, an identified BDFT model is used off-line to generate an estimate of the involuntary control inputs based on the accelerations present. Results show that reliable signal cancellation requires BDFT models that are both subject and task dependent. The task dependency is of particular importance: failing to adapt the model to changes in the operator's neuromuscular dynamics dramatically decreases the quality of cancellation and can even lead to an increase in unwanted effects. As a reliable and fast on-line identification method of the neuromuscular dynamics of the human operator currently does not exist, real-time signal cancellation is currently not feasible.nonotspecifiedhttp://www.cyberneum.de/published5Cancelling biodynamic feedthrough requires a subject and task dependent approach1501715422SonCKB20117HISonLChuangJKimHHBülthoffGyeonggi-do, Korea2011-10-001323132811th International Conference on Control, Automations and Systems (ICCAS 2011)The availability of additional force cues in haptic devices are often expected to improve control performance, over conditions that only provide visual feedback. However, there is little empirical evidence to show this to be true for the teleoperation control of remote vehicles (i.e., multiple unmanned aerial vehicles (UAVs)). In this paper, we show that force cues can increase one's sensitivity in discerning the presence of obstacles in the remote multi-UAVs' environment. Significant benefits, relative to a purely visual scenario, were achieved only when force cues were sufficiently amplified by large gains. In addition, force cues tended to provide stronger benefits when they were based on the UAVs' velocity information.nonotspecifiedhttp://www.cyberneum.de/published5Haptic Feedback Cues Can Improve Human Perceptual Awareness in Multi-Robots Teleoperation1501715422LayherTSBCN20117GLayherSTschechneSSchererTBroschCCurioHNeumannBerlin, Germany2011-10-00239Workshop on "Companion-Systeme und Mensch-Companion-Interaktion"Companion technologies aim at developing sustained long-term relationships by employing emotional, nonverbal communication skills and empathy. One of the main challenges is to equip such companions with human-like abilities to reliably detect and analyze social signals. In this proposal, we focus our investigation on the modeling of visual processing mechanisms, since evidence in literature suggests that nonverbal interaction plays a key role in steering, controlling and maintaining social
interaction between humans. We seek to transfer fragments of this competence to the domain of human computer interaction. Some core computational mechanisms of
extracting and analyzing nonverbal signals are presented, enabling virtual agents to create socially competent response behaviors.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/Informatik-2011-Layher.pdfpublished-239Social Signal Processing in Companion Systems: Challenges Ahead1501715422TsiatsisN20117PTsiatsisUNoppeneyHeiligkreuztal, Germany2011-10-004412th Conference of Junior Neuroscientists of Tübingen (NeNA 2011)Neuronal oscillations are considered crucial for information processing in the brain as they can
potentially regulate information flow and dynamically bind different cortical and non-cortical
regions. This MEG study investigated whether the effect of a transient sound was modulated
by the phase of oscillations in the visual cortex. To induce steady state oscillations in the
visual cortex, we presented subjects with continuous visual signals luminance-modulated at
4Hz or 10Hz. The transient sounds were presented locked to four phases of the periodic visual
stimulus (i.e. 0, 1
2, , 3
4). We then investigated whether the effect of sound depends on
the phase of the visual steady state activity by testing for the interaction between sound
and visual phase. Conversely, we will investigate the effect of the sound processing on the
visual steady state processing given the state of the visual cortex. The results from the two
experiments (4Hz & 10Hz) will be combined and compared. Based on recent neurophysiological
evidence, we hypothesize that oscillations at different frequencies play distinct functional
roles in multisensory integration.nonotspecifiedhttp://www.cyberneum.de/published-44Auditory Processing under Steady State Visual Driving15017154221501718826SchindlerKB2011_27ASchindlerMKleinerABartelsHeiligkreuztal, Germany2011-10-004012th Conference of Junior Neuroscientists of Tübingen (NeNA 2011)In our subjective experience, there is a tight link between covert visual attention and egocentric
spatial attention. One key difference is that the latter can extend beyond the visual
field, providing us with an acurate mental representation of an object’s location relative to
our body position. A neural link between visual and ego-centric spatial attention is suggested
by lesions in parietal cortex, that lead not only to deficits in covert visual attention, but
frequently also to a disorder of ego-centric spatial awareness, known as hemi-spatial neglect.
While parietal involvement in covert visual spatial attention has been much studied, relatively
little is known about mental representations of the unseen space around. In the present study
we examined whether also unseen spatial locations beyond the visual field are represented
in parietal activity, and how they are related to retinotopic representations. We employed a
novel virtual reality (VR) paradigm during functional magnetic resonance imaging (fMRI),
whereby observers were prompted to draw their spatial attention to the position of one of
eight possible objects located around them in an octagonal room. By changing the observers’
facing direction every few trials, the ego-centric location of objects was disentangled from their
absolute position and from the objectsâ identity. Thus, mental representations of egocentric
space surrounding the observer were sampled eight-fold. Decoding results of a multivariate
pattern analysis classifier (MVPA), but not univariate results, showed that egocentric spatial
directions were specifically represented in parietal cortex. These representations overlapped
only partly with visually driven retinotopic activity. Our results thus show that parietal cortex
codes not only for retinotopic and visually accessible space, but also for ego-centric locations
of the three-dimensional space surrounding us, including unseen space.nonotspecifiedhttp://www.cyberneum.de/published-40Decoding Egocentric Space in human Posterior Parietal Cortex using fMRI15017154211501715422LeeBBC20117JJLeeH-JBiegHHBülthoffLLChuangHeiligkreuztal, Germany2011-10-003312th Conference of Junior Neuroscientists of Tübingen (NeNA 2011)How does our visual system decide where to look? The Linear Approach to Threshold with
Ergodic Rate (LATER: Carpenter, 1995) is a simple decision-making model for saccadic
eye movements. Currently, experimental data suggest that saccadic eye-movements can be
discriminated according to whether they are performed for directed fixations or for item
recognition (Montagnini & Chelazzi, 2005; Bieg et al., submitted). Unfortunately, sufficient
goodness-of-fit can only be acquired with large datasets, for each individual participant. Here,
we investigate whether adapting LATER with modern computational methods can allow for
saccades to be classified for their functionality, with minimal data and in real-time. In doing
so, we strive towards the eventual goal of using the LATER model for predicting observer
intentions in real-world applications.nonotspecifiedhttp://www.cyberneum.de/published-33Fast Fitting on a Saccadic Eye Movement Model for Decision Making1501715422PapeWSBM2011_27A-APapeTWolbersJSchultzHHBülthoffTMeilingerHeiligkreuztal, Germany2011-10-003812th Conference of Junior Neuroscientists of Tübingen (NeNA 2011)Grid cells in entorhinal cortex of freely moving rodents were proposed to provide a universal
metric of space. They tile the environment into a six-fold symmetric pattern with a particular
orientation relative to the environment. The six-fold rotational symmetry of grid patterns can
be used to predict a macroscopic signal to functional magnetic resonance imaging (fMRI) in
humans [Doeller et al, 2010, Nature]. During hippocampal remapping, grid pattern orientations
in rats also change. The purpose of the present study is to examine whether orientation
changes (i.e. remapping) can also be found in humans. Participants learned object locations
within a virtual room and retrieved locations from different start locations during two scanning
sessions. They then navigated into an adjacent room and repeated the procedure. We
extracted grid orientations from odd trials, and predicted the BOLD response in even trials as
a function of the deviation between running direction and the estimated grid orientation for
each session. This prediction was significant for the right entorhinal cortex, replicating earlier
findings. In 80% of the cases grid cell orientations significantly differed between sessions both
within a room and between rooms. Switching off the virtual environment between sessions
for about one minute was seemingly sufficient for that. For male, but not for female participants,
grid cell orientation was clustered around the random view of the room experienced
at session start. Data suggests that human grid cell orientations can be rather flexible which
might be due to the virtuality of the experience. Grid cell orientation might at least for male
participants be related to the initial view of an environment.nonotspecifiedhttp://www.cyberneum.de/published-38Grid cell remapping in humans1501715422SoykaBRB20117FSoykaMBarnett-CowanPRobuffo GiordanoHHBülthoffHeiligkreuztal, Germany2011-10-004212th Conference of Junior Neuroscientists of Tübingen (NeNA 2011)During eccentric yaw rotations around an Earth-vertical axis the semi-circular canals are
stimulated (rotational acceleration) as well as the otoliths (tangential acceleration). Most
likely the brain uses both sensory signals, the canal and the otolith signal, when faced with a
rotation direction detection task. Keeping the rotational acceleration profile unchanged and
increasing the radius of the eccentric rotation the tangential acceleration increases. Therefore,
we hypothesized that thresholds would decrease with increasing radius of rotation. The
threshold was defined as the peak acceleration needed to detect the correct direction of motion
in 75% of the trials. Ten participants were tested in seven conditions (150 trials each): a
head-centered rotation, a translation and five eccentric rotations with varying radii (R=0.1,
0.2, 0.3, 0.5, 0.8 m). The motion had 1s duration and consisted of a single cycle sinusoidal
acceleration. Participants were blindfolded, heard white noise and their head was kept in
place with a neck brace. The results show a significant decrease of thresholds with increasing
radius. It can be seen that the detection process for eccentric rotations is not exclusively
based on either the canal or the otolith signal, but that both signals are integrated. A model
able to predict the thresholds of the eccentric rotations is proposed, which is solely based on
the thresholds for the head-centered rotation and the translational motion. For small radii the
detection processes is mainly based on the canal signal whereas for large radii it is dominated
by the otolith signal. For intermediate radii the reduction in threshold due to the sensory
combination is largest compared to using only one of the two sensors. One additional participant
suffered from occasional vertigo after an ear infection indicating vestibular problems.
She showed unusually high thresholds for translational motions, but normal thresholds for
head-centered rotations. Interestingly, her thresholds for eccentric rotations were higher than
her threshold for the head-centered rotations suggesting that she did not only use the rotational
signal, but instead had a problem integrating the two sensory signals. These findings
indicate that signals from the otolith and the semi-circular canals are not used independently,
but are integrated in order to solve a direction detection task.nonotspecifiedhttp://www.cyberneum.de/published-42Integration of Translational and Rotational Vestibular Cues for Direction Detection during Eccentric Rotations1501715422GianiEBKPN20117AGianiOErickPBelardinelliMKleinerHPreisslUNoppeneyHeiligkreuztal, Germany2011-10-002712th Conference of Junior Neuroscientists of Tübingen (NeNA 2011)To form a unified percept of our environment, the human brain integrates information within
and across the senses. This MEG study investigated interactions within and between sensory
modalities using a frequency analysis of steady-Ââstate responses (SSR) to periodic auditory
and/or visual inputs. The 3x3 factorial design, manipulated (1) modality (auditory only, visual
only and audiovisual) and (2) temporal dynamics (static, dynamic1 and dynamic2). In
the static conditions, subjects were presented with (1) visual gratings, luminance modulated
at 6Hz and/or (2) pure tones, frequency modulated at 40 Hz. To manipulate perceptual synchrony,
we imposed additional slow modulations on the auditory and visual stimuli either at
same (0.2 Hz = synchronous) or different frequencies (0.2 Hz vs. 0.7 Hz = asynchronous).
This also enabled us to investigate the integration of two dynamic features within one sensory
modality (e.g. a pure tone frequency modulated at 40Hz & amplitude modulated at 0.2Hz)
in the dynamic conditions. We reliably identified crossmodulation frequencies when these
two stimulus features were modulated at different frequencies. In contrast, no crossmodulation
frequencies were identified when information needed to be combined from auditory
and visual modalities. The absence of audiovisual crossmodulation frequencies suggests that
the previously reported audiovisual interactions in primary sensory areas may mediate low
level spatiotemporal coincidence detection that is prominent for stimulus transients but less
relevant for sustained SSR responses. In conclusion, our results indicate that information in
SSRs is integrated over multiple time scales within but not across sensory modalities at the
primary cortical level.nonotspecifiedhttp://www.cyberneum.de/published-27Steady-state responses in MEG demonstrate information integration within but not across the auditory and visual senses15017154221501718826RoheN20127TRoheUNoppeneyHeiligkreuztal, Germany2011-10-003912th Conference of Junior Neuroscientists of Tübingen (NeNA 2011)Humans integrate auditory and visual spatial cues to locate objects. Generally, location judgments are dominated by vision because observers localize an auditory cue close to a visual cue even if they have been instructed to ignore the latter (ventriloquist effect). A recent model of
multisensory integration proposes that the ventriloquist effect is governed by two principles: First, spatially discrepant cues are only integrated if the observer infers that both cues stem from one object (principle of causal inference). Second, if the inference results in an assumption that both cues originate from one object the cues are integrated by weighting them according to their relative reliability (principle of Bayes-optimal cue weighting). Thus, the bimodal estimate of the object`s location has a higher reliability than each of the unisensory estimates per se. In order to test this model, 26 subjects were presented with spatial auditory
(HRTF-convolved white noise) and visual cues (cloud of dots). The 5x5x5 factorial design manipulated (1) the auditory cue location, (2) the visual cue location and (3) the reliability of the visual cue via the width of the cloud of dots. Subjects were instructed to locate the
auditory cue while ignoring the visual cue and to judge the spatial unity of both cues. In line with the principle of causal inference results showed that the ventriloquist effect was weaker and unity judgments were reduced for larger audiovisual discrepancies. In case of small spatial
discrepancies the ventriloquist effect was weaker at low levels of visual reliability implying a Bayes-optimal strategy of cue weighting only if a common cause of both cues was assumed. A probabilistic model incorporating the principles of causal inference and Bayes-optimal cue
weighting accurately fitted the behavioral data. Overall, the pattern of results suggested that both principles describe important processes governing multisensory integration.nonotspecifiedhttp://www.cyberneum.de/published-39The ventriloquist effect depends on audiovisual spatial discrepancy and visual reliability15017154221501718826Kleiner201110MKleinerChuang2011_310LChuangChuang2011_210LChuangBulthoff2011_910HHBülthoffBulthoff2011_710HHBülthoffSchomakerTBB20113JSchomakerJTeschHHBülthoffJPBresciani2011-09-002-3243245256Experimental Brain ResearchParticipants performed a visual–vestibular motor recalibration task in virtual reality. The task consisted of keeping the extended arm and hand stable in space during a whole-body rotation induced by a robotic wheelchair. Performance was first quantified in a pre-test in which no visual feedback was available during the rotation. During the subsequent adaptation phase, optical flow resulting from body rotation was provided. This visual feedback was manipulated to create the illusion of a smaller rotational movement than actually occurred, hereby altering the visual–vestibular mapping. The effects of the adaptation phase on hand stabilization performance were measured during a post-test that was identical to the pre-test. Three different groups of subjects were exposed to different perspectives on the visual scene, i.e., first-person, top view, or mirror view. Sensorimotor adaptation occurred for all three viewpoint conditions, performance in the post-test session showing a marked under-compensation relative to the pre-test performance. In other words, all viewpoints gave rise to a remapping between vestibular input and the motor output required to stabilize the arm. Furthermore, the first-person and mirror view adaptation induced a significant decrease in variability of the stabilization performance. Such variability reduction was not observed for the top view adaptation. These results suggest that even if all three viewpoints can evoke substantial adaptation aftereffects, the more naturalistic first-person view and the richer mirror view should be preferred when reducing motor variability constitutes an important issue.nonotspecifiedhttp://www.cyberneum.de/published11It is all me: the effect of viewpoint on visual-vestibular recalibration1501715422BulthoffC20113HHBülthoffLLChuang2011-09-00386227Quarterly Review of Biologynonotspecifiedhttp://www.cyberneum.de/published-227Seeing: The Computational Approach to Biological Vision. Second Edition. By John P. Frisby and James V. Stone. Cambridge (Massachusetts): MIT Press1501715422GaissertBW20113NGaissertHHBülthoffCWallraven2011-09-001138219230Acta PsychologicaEven though human perceptual development relies on combining multiple modalities, most categorization studies so far have focused on the visual modality. To better understand the mechanisms underlying multisensory categorization, we analyzed visual and haptic perceptual spaces and compared them with human categorization behavior. As stimuli we used a three-dimensional object space of complex, parametrically-defined objects. First, we gathered similarity ratings for all objects and analyzed the perceptual spaces of both modalities using multidimensional scaling analysis. Next, we performed three different categorization tasks which are representative of every-day learning scenarios: in a fully unconstrained task, objects were freely categorized, in a semi-constrained task, exactly three groups had to be created, whereas in a constrained task, participants received three prototype objects and had to assign all other objects accordingly. We found that the haptic modality was on par with the visual modality both in recovering the topology of the physical space and in solving the categorization tasks. We also found that within-category similarity was consistently higher than across-category similarity for all categorization tasks and thus show how perceptual spaces based on similarity can explain visual and haptic object categorization. Our results suggest that both modalities employ similar processes in forming categories of complex objects.nonotspecifiedhttp://www.cyberneum.de/published11Similarity and categorization: From vision to touch1501715422ButlerCBS20113JSButlerJLCamposHHBülthoffSTSmith2011-09-00524453470Seeing and PerceivingSelf-motion through an environment stimulates several sensory systems, including the visual system and the vestibular system. Recent work in heading estimation has demonstrated that visual and vestibular cues are typically integrated in a statistically optimal manner, consistent with Maximum Likelihood Estimation predictions. However, there has been some indication that cue integration may be affected by characteristics of the visual stimulus. Therefore, the current experiment evaluated whether presenting optic flow stimuli stereoscopically, or presenting both eyes with the same image (binocularly) affects combined visual-vestibular heading estimates.
Participants performed a two-interval forced-choice task in which they were asked which of two presented movements was more rightward. They were presented with either visual cues alone, vestibular cues alone or both cues combined. Measures of reliability were obtained for both binocular and stereoscopic conditions.
Group level analyses demonstrated that when stereoscopic information was available there was clear evidence of optimal integration, yet when only binocular information was available weaker evidence of cue integration was observed. Exploratory individual analyses demonstrated that for the stereoscopic condition 90% of participants exhibited optimal integration, whereas for the binocular condition only 60% of participants exhibited results consistent with optimal integration. Overall, these findings suggest that stereo vision may be important for self-motion perception, particularly under combined visual-vestibular conditions.nonotspecifiedhttp://www.cyberneum.de/published17The Role of Stereo Vision in Visual-Vestibular Integration1501715422FranchiMBR20117AFranchiCMasoneHHBülthoffPRobuffo GiordanoSan Francisco, CA, USA2011-09-0022152222IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2011)We present a decentralized system for the bilateral teleoperation of groups of UAVs which only relies on relative bearing measurements, i.e., without the need of distance information or global localization. The properties of a 3D bearing-formation are analyzed, and a minimal set of bearings needed for its definition is provided. We also design a novel decentralized formation control almost globally convergent and able to maintain bounded and non-vanishing inter-distances among the agents despite the absence of direct distance measurements. Furthermore, we develop a multi-master/ multi-slave teleoperation setup in order to control the overall behavior of the group and to convey to the human operator suitable force cues, while ensuring stability in presence of delays and packet losses over the master-slave communication channel. The theoretical framework is validated by means of extensive human/hardware in-the-loop simulations using two force-feedback devices and a group of quadrotors.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/IROS-2011-Franchi.pdfpublished7Bilateral teleoperation of multiple UAVs with decentralized bearing-only formation control150171542268457SMCAlaimoLPolliniJ-PBrescianiHHBülthoffMilano, Italy2011-09-006472647718th World Congress of the International Federation of Automatic Control (IFAC World 2011)The sense of telepresence is very important in teleoperation environments in which the operator is physically separated from the vehicle. It appears reasonable, and it has already been shown in the literature, that extending the visual feedback with force feedback is able to complement the visual information (when missing or limited) through the sense of touch and allows the operator to better perceive information from the remote environment and its constraints, hopefully preventing dangerous collisions. This paper focuses on a novel concept of haptic cueing for an airborne obstacle avoidance task; the novel cueing algorithm was designed in order to appear “natural” to the operator, and to improve the human-machine interface without directly acting on the actual aircraft commands. An experimental evaluation of two different Haptic aiding concepts for obstacle avoidance is presented. An existing and widely used approach, belonging to what we called the Direct Haptic Aid (DHA) class, and a novel one based on the Indirect Haptic Aid (IHA) class. The two haptic aids were compared with a baseline condition in which no haptic force was associated to the obstacles. Test results show that a net improvement in terms of performance (i.e. the number of collisions) is provided by employing the IHA haptic cue instead of both the DHA haptic cue and the visual cue only. Most participants of the experiment reported the strongest force feeling, the most necessary effort and also the most helpful sensation with DHA and IHA conditions with respect to the baseline condition. This paper shows that the IHA philosophy is a valid alternative to the other commonly used, and published in the scientific literature, approaches which fall in the DHA category.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/IFAC-2011-Alaimo.pdfpublished5Evaluation of Direct and Indirect Haptic Aiding in an Obstacle Avoidance Task for Tele-Operated Systems1501715422RobuffoGiordanoFSB2011_27PRobuffo GiordanoAFranchiCSecchiHHBülthoffSan Francisco, CA, USA2011-09-00163170IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2011)In this paper, we present an experimental validation of a novel decentralized passivity-based control strategy for teleoperating a group of Unmanned Aerial Vehicles (UAVs): the slave side, consisting of the UAVs, is endowed with large group autonomy by allowing time-varying topology and interrobot/obstacle collision avoidance. The master side, represented by a human operator, controls the group motion and receives suitable force feedback cues informing her/him about the remote slave motion status. Passivity theory is exploited for guaranteeing stability of the slave side and of the overall teleoperation channel. Results of experiments involving the use of 4 quadcopters are reported and discussed, confirming the soundness of the paper theoretical claims.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/2011k-RobFraSecBue-preprint.pdfpublished7Experiments of passivity-based bilateral aerial teleoperation of a group of UAVs with decentralized velocity synchronization1501715422EngelBHC20117DEngelCHerdtweckBBrowatzkiCCurioLisboa, Portugal2011-09-0041242513th IFIP TC13 Conference on Human-Computer InteractionWith increasingly large image databases, searching in them becomes an ever more difficult endeavor. Consequently, there is a need for advanced tools for image retrieval in a webscale context. Searching by tags becomes intractable in such scenarios as large numbers of images will correspond to queries such as “car and house and street”. We present a novel approach that allows a user to search for images based on semantic sketches that describe the desired composition of the image. Our system operates on images with labels for a few high-level object categories, allowing us to search very fast with a minimal memory footprint. We employ a structure similar to random decision forests which avails a data-driven partitioning of the image space providing a search in logarithmic time with respect to the number of images. This makes our system applicable for large scale image search problems. We performed a user study that demonstrates the validity and usability of our approach.nonotspecifiedhttp://www.cyberneum.de/published13Image Retrieval with Semantic Sketches1501715422SonCFKLLBR20117HISonLLChuangAFranchiJKimDLeeS-WLeeHHBülthoffPRobuffo GiordanoSan Francisco, CA, USA2011-09-0030393046IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2011)In this paper, we investigate the maneuverability performance of human teleoperators on multi-robots. First, we propose that maneuverability performance can be assessed by a frequency response function that jointly considers the input force of the operator and the position errors of the multi-robot system that is being maneuvered. Doing so allows us to evaluate maneuverability performance in terms of the human teleoperator's interaction with the controlled system. This allowed us to effectively determine the suitability of different haptic cue algorithms in improving teleoperation maneuverability. Performance metrics based on the human teleoperator's frequency response function indicate that maneuverability performance is best supported by a haptic feedback algorithm which is based on an obstacle avoidance force.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/IROS-2011-Son.pdfpublished7Measuring an Operator's Maneuverability Performance in the Haptic Teleoperation of Multiple Robots1501715422NolanBWFBR2011_37HNolanJSButlerRWhelanJJFoxeHHBülthoffRBReillyBoston, MA, USA2011-09-0038843887Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2011)The technical challenges of recording electroencephalographic (EEG) data during motion are considerable, but would enable the possibility of investigating neural function associated with balance, motor function and motion perception. The challenges include finding a reliable method of motion stimulus reproduction, removing artifacts, and ensuring that the recordings retain sufficient EEG signal for proper interpretation. This study details the use of the P3 waveform to validate the concept of motion-based EEG data, and discusses some potential future uses in experimental and clinical settings.nonotspecifiedhttp://www.cyberneum.de/published3Motion P3 demonstrates neural nature of motion ERPs1501715422StegagnoCFO20117PStegagnoMCognettiAFranchiGOrioloSan Francisco, CA, USA2011-09-00469474IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2011)This paper addresses the problem of mutual localization in multi-robot systems in presence of anonymous (i.e., without the identity information) bearing-only measurements. The solution of this problem is relevant for the design and implementation of any decentralized multi-robot algorithm/control. A novel algorithm for probabilistic multiple registration of these measurements is presented, where no global localization, distances, or identity are used. With respect to more conventional solutions that could be conceived on the basis of the current literature, our method is theoretically suitable for tasks requiring frequent, many-to-many encounters among agents (e.g., formation control, cooperative exploration, multiple-view environment sensing). An extensive experimental study validates our method and compares it with the full-informative case of bearing-plus-distance measurements. The results show that the proposed localization system exhibits an accuracy commensurate to our previous method [1] which uses bearing-plus-distance information.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/IROS-2011-Stegnano.pdfpublished5Mutual localization using anonymous bearing measurements1501715422GaissertWvB20117NGaissertSWaterkampLvan DamIBülthoffToulouse, France2011-09-0013434th European Conference on Visual PerceptionWhen humans have to categorize objects they often rely on shape as a deterministic feature. However, shape is not exclusive to the visual modality: the haptic system is also an expert in identifying shapes. This raises the question whether humans store separate modality-dependent shape representations or if one multimodal representation is formed. To better understand how humans categorize objects based on shape we created a set of computer-generated amoeba-like objects varing in defined shape steps. These objects were then printed using a 3D printer to generate tangible stimuli. In a discrimination task and a categorization task, participants either visually or haptically explored the objects. We found that both modalities lead to highly similar categorization behavior indicating that the processes underlying categorization are highly similar in both modalities. Next, participants were trained on special shape categories by using the visual modality alone or by using the haptic modality alone. As expected, visual training increased visual performance and haptic training increased haptic performance. Moreover, we found that visual training on shape categories greatly improved haptic performance and vice versa. Our results point to a shared representation underlying both modalities, which accounts for the surprisingly strong transfer of training across the senses.nonotspecifiedhttp://www.cyberneum.de/published-134Cross-modal transfer in visual and haptic object categorization1501715422ElzeT20117TElzeTTannerToulouse, France2011-09-0017534th European Conference on Visual PerceptionIn most areas of vision science, liquid crystal displays (LCDs) have widely replaced the long dominating cathode ray tube (CRT) technology. In recent years, however, LCD panels have been repeatedly analyzed and their use been criticized with reference to vision science applications. We measured and analyzed the photometric output of eleven contemporary LCD monitors. Our results show that the specifications given by the manufacturers are partially misleading and mostly insufficient for appropriate display selection for many vision science related tasks. In recent years, novel display technologies have been introduced to improve fast luminance transitions or to optimize the appearance of moving objects. While we found that the luminance transition times of modern LCD monitors are considerably faster than those of earlier LCD generations, these novel technologies may be accompanied by side effects relevant to vision research. Furthermore, we demonstrate a number of intriguing technical deficiencies which may severely impair visual experiments. Several undesired und uncontrolled components of the photometric output as well as unreliable onsets and offsets of visual stimuli require ample measurements prior to applications in all areas of vision science where either precise timing or the knowledge of the exact shape of the photometric output signal matters.nonotspecifiedhttp://www.cyberneum.de/published-175Dangerous liquids: Temporal properties of modern LCD monitors and implications for vision science experiments1501715422SchultzB20117JSchultzHHBülthoffNaples, FL, USA2011-09-0068211th Annual Meeting of the Vision Sciences Society (VSS 2011)Identifying living moving things in the environment is a priority for animals, as these could be prey, enemies or mates. When the shape of the moving object is hard to see (fog, twilight, great distance, small animal), motion becomes an important cue to detect it. The neural correlates of the detection of an isolated living entity on the basis of its motion are largely unknown.
To study this phenomenon, we developed a single-dot stimulus, thus eliminating all possible sources of information about form, spatial arrangement, shape or structure of the object. The dot moved such that it appeared self-propelled, or moved by an external force, or something intermediary according to a small set of parameters. Self-propelled stimuli were perceived as more animate (= more likely to be alive) than the externally-moved stimuli, with a gradual transition occurring in the intermediary morphs following a classic psychometric function (cumulative gaussian).
In an fMRI experiment, 20 subjects had to categorize these stimuli into alive and non-alive. A region of the left medial posterior parietal cortex (mPPC) showed BOLD signal correlating with the probability of animacy judgments about the moving dot. While activation in parts of the early visual cortex showed the same response, the mPPC was the only region in which changes in percept had a stronger effect on activation than physical changes in the stimuli. In addition, only the mPPC showed BOLD signal increases when a stimulus was judged to be animate, irrespective of its physical characteristics.
This study shows that parts of the early visual cortex but particularly the medial posterior parietal cortex (mPPC) are involved in judging the animacy of an isolated translating visual stimulus, without information about its form.nonotspecifiedhttp://www.cyberneum.de/published-682How does the brain identify living things based on their motion?1501715422ThorntonHB20117IMThorntonTSHorowitzHHBülthoffNaples, FL, USA2011-09-0029311th Annual Meeting of the Vision Sciences Society (VSS 2011)We introduce a novel, iPad-based experimental paradigm to study interactive multiple object tracking (MOT). In standard MOT, participants passively track a set of independently moving objects. We devised a new task in which participants interact with objects, rather than simply track them. We combined a typical MOT display with the path-guidance, touch-screen interface popularised in smart phone games such as Flight Controller and Harbor Master. We ran the experiment using a custom iPad application. A variable number of identical spheres (1.16° visual angle) moved slowly (0.89°/s) on independent linear trajectories within the full iPad display area (22.6° × 17°). Random direction changes occurred at intervals between 4 and 7 s. The participant's goal was to avoid object collisions by manually altering the sphere trajectories. This was achieved by touching the sphere and drawing a short linear or curved path away from it. This action created a visible path, which the sphere followed before resuming default random motion. In this initial study, we constrained path length, in order to prevent participants from creating complex “holding patterns”. A trial ended when the participant successfully avoided collisions for 30 s or when a collision occurred. A sphere was added to the display after a successful trial and removed after a collision, subject to a 6-sphere minimum. Twenty-four participants (ages 18 to 33, mean 23.58, sd 3.45); twelve from Korea University, twelve from Swansea University) completed 30 trials. There were no significant effects of culture, sex or previous gaming experience. The mean number of spheres participants could control was 8.39 (s.e.m. 0.14). This is consistent with estimates of passive tracking capacity at slow speeds. We hypothesize that executive control of scant attentional resources is critical for the current task. In support of this hypothesis, interactive tracking capacity actually increased with age (p = .016).nonotspecifiedhttp://www.cyberneum.de/published-293iMOT: interactive Multiple Object Tracking1501715422VolkovaLABM20117EVolkovaSLinkenaugerIAlexandrovaHHBülthoffBMohlerToulouse, France2011-09-0013834th European Conference on Visual PerceptionVirtual characters are a potentially valuable tool for creating stimuli for research investigating the perception of emotion. We conducted an audio-visual experiment to investigate the effectiveness of our stimuli to convey the intended emotion. We used dynamic virtual faces in addition to pre-recorded (Burkhardt et al, 2005, Interspeech'2005, 1517–1520) and synthesized speech to create audio-visual stimuli which conveyed all possible combinations of stimuli. Each voice and face stimuli aimed to express one of seven different emotional categories. The participants made judgments of the prevalent emotion. For the pre-recorded voice, the vocalized emotion influenced participants’ emotion judgment more than the facial expression. However, for the synthesized voice, facial expression influenced participants’ emotion judgment more than vocalized emotion. While participants rather accurately labeled (>76%) the stimuli when face and voice emotion were the same, they performed worse overall on correctly identifying the stimuli when the voice was synthesized. We further analyzed the difference between the emotional categories in each stimulus and found that valence distance in the emotion of the face and voice significantly impacted recognition of the emotion judgment for both natural and synthesized voices. This experimental design provides a method to improve virtual character emotional expression.nonotspecifiedhttp://www.cyberneum.de/published-138Integration of Visual and Auditory Stimuli in the Perception of Emotional Expression in Virtual Characters1501715422DobsKBSC20117KDobsMKleinerIBülthoffJSchultzCCurioToulouse, France2011-09-0011534th European Conference on Visual Perception3D facial animation systems allow the creation of well-controlled stimuli to study face processing. Despite this high level of control, such stimuli often lack naturalness due to artificial facial dynamics (eg linear morphing). The present study investigates the extent to which human visual perception can be fooled by artificial facial motion. We used a system that decomposes facial motion capture data into time courses of basic action shapes (Curio et al, 2006 APGV 1 77–84). Motion capture data from four short facial expressions were input to the system. The resulting time courses and five approximations were retargeted onto a 3D avatar head using basic action shapes created manually in Poser. Sensitivity to the subtle modifications was measured in a matching task using video sequences of the actor performing the corresponding expressions as target. Participants were able to identify the unmodified retargeted facial motion above chance level under all conditions. Furthermore, matching performance for the different approximations varied with expression. Our findings highlight the sensitivity of human perception for subtle facial dynamics. Moreover, the action shape-based system will allow us to further investigate the perception of idiosyncratic facial motion using well-controlled facial animation stimuli.nonotspecifiedhttp://www.cyberneum.de/published-115Investigating idiosyncratic facial dynamics with motion retargeting1501715422ProctorCBT20117KJProctorMChenHHBülthoffIMThrorntonToulouse, France2011-09-0020634th European Conference on Visual PerceptionBody sway—the subtle, low frequency movement of the human body measured during quiet-standing—has long been used as a tool to help diagnose a range of medical conditions. It can be measured in a number of ways, including force platforms, sway magnetometry and marker or marker-less motion capture. In the current work—by analogy—we examined whether “iPad sway” could be used as an indirect measure of performance in a simple interactive task. We asked participants to stand and play a simple iPad game that involved tracking and controlling multiple objects using the touch screen. In addition to measuring variations in task performance as a function of set size and object speed, we also used the iPad’s built-in accelerometer to record changes in applied force along three axes. Analysis of this force data revealed both task relevant and task irrelevant components. The former relating directly to task demands—particularly touching the screen—and the latter reflecting idiosyncratic posture and movement patterns that can be used to uniquely identify individual users.nonotspecifiedhttp://www.cyberneum.de/published-206iPad sway: Using mobile devices to indirectly measure performance1501715422deWinkelSBGB20117KNde WinkelFSoykaMBarnett-CowanEGroenHHBülthoffToulouse, France2011-09-0018334th European Conference on Visual PerceptionNumerous studies report that humans integrate multisensory information in a statistically optimal fashion. However, with respect to self-motion perception, results are inconclusive. Here we test the hypothesis that visual and inertial cues in simulator environments are optimally integrated and that this integration develops over time. Eight participants performed a 2AFC discrimination experiment in visual-only, inertial-only and visual-inertial conditions. Conditions were repeated three times. Inertial motion stimuli were one-period 0.5 Hz sinusoidal acceleration profiles. Visual stimuli were videos of a vertical stripe pattern synchronized with inertial motion. Stimuli were presented in pairs with different peak velocity amplitudes. Participants judged which rotation of a pair had the highest velocity. Precision estimates were derived from psychometric functions. Optimal integration predicts improved precision in the combined condition. However, precision did not differ between the visual and combined conditions. This suggests that participants based their responses predominantly on visual motion. Alternatively, the results could be consistent with optimal integration if the assumption that visual precision remains unchanged during inertial motion was violated. We suggest that a change in visual sensitivity should be considered when investigating optimal integration of visual and inertial cues.nonotspecifiedhttp://www.cyberneum.de/published-183Multisensory integration in the perception of self-motion about an Earth-vertical yaw axis1501715422ChuangS20117LLChuangJLSoumanTübingen, Germany2011-09-00Bernstein Cluster D Symposium: Multisensory Perception and Actionnonotspecifiedhttp://www.cyberneum.de/published0Object speed estimation during walking does not add up1501715422LeyrerLBKM2011_37MLeyrerSALinkenaugerHHBülthoffUKloosBJMohlerToulouse, France2011-09-0020934th European Conference on Visual PerceptionNewer technology allows for more realistic virtual environments by providing visual image quality that is very similar to that in the real world, this includes adding in virtual self-animated avatars [Slater et al, 2010 PLoS ONE 5(5); Sanchez-Vives et al, 2010 PLoS ONE 5(4)]. To investigate the influence of relative size changes between the visual environment and the visual body, we immersed participants into a full cue virtual environment where they viewed a self-animated avatar from behind and at the same eye-height as the avatar. We systematically manipulated the size of the avatar and the size of the virtual room (which included familiar objects). Both before and after exposure to the virtual room and body, participants performed an action-based measurement and made verbal estimates about the size of self and the world. Additionally we measured their subjective sense of body ownership. The results indicate that the size of the self-representing avatar can change how the user perceives and interacts within the virtual environment. These results have implications for scientists interested in visual space perception and also could potentially be useful for creating positive visual illusions (ie the feeling of being in a more spacious room).nonotspecifiedhttp://www.cyberneum.de/published-209Perception of the size of self and the surrounding visual world in immersive virtual environments1501715422diLucaMBE20117MDi LucaTMachullaMBarnett-CowanMOErnstTübingen, Germany2011-09-00Bernstein Cluster D Symposium: Multisensory Perception and Actionnonotspecifiedhttp://www.cyberneum.de/published0Recalibration of audiovisual simultaneity15017154221501718824ChuangBS20117LChuangHHBülthoffJSoumanToulouse, France2011-09-0012934th European Conference on Visual PerceptionWalking reduces visual speed estimates of optic flow (Souman et al, 2010 Journal of Vision 10(11):14]. Simultaneously, visual background motion can influence the perceived speed of moving objects (Tynan and Sekular, 1975 Vision Research 25 1231–1238; Baker and Graf, 2010 Vision Research 50 193–201). These two effects have been attributed to different subtractive processes, which may help in segregating object motion from self-motion induced optic flow. Here, we investigate how both factors jointly contribute to the perceived visual speed of objects. Participants compared the speed of two central Gabor patches on a ground plane, presented in consecutive intervals, either while standing still or while walking on a treadmill. In half the trials, one of the Gabors was surrounded by a moving random dot pattern, the speed of which matched walking speed. Our results replicated previous findings. A moving surround as well as walking can independently induce a subtractive effect on the perceived speed of the moving center, with the effect size increasing with center speed. However, walking does not affect visual speed estimates of the center when a visual surround is present. These results suggest that the visual input dominates the segregation of object motion from background optic flow.nonotspecifiedhttp://www.cyberneum.de/published-129The center-surround effect in visual speed estimation during walking1501715422Streuberd20117SStreuberSde la RosaToulouse, France2011-09-0022634th European Conference on Visual PerceptionSeeing an object is important for motor control during object interaction. Which sources of visual information are important for motor control in social interaction? In a virtual environment participants hit table tennis balls served by a virtual player. We manipulated the visibility of visual information (ball, racket, body) about the virtual player and the presentation time of the animation (before, during, and after the virtual player’s stroke). We measured the shortest distance between the ball and the participants’ racket. Results: (1) The visibility of each source of information was associated with performance increases; (2) performance did not change when visual information was presented after the virtual player hit the ball; (3) the presentation of the virtual player's racket induced the largest performance improvement shortly before the virtual player hit the ball; (4) performance changes associated with seeing the virtual player’s body were independent of presentation time. In sum participants seem to use multiple sources of visual information about the interaction partner. Moreover visual information about the interaction partner is most useful when seen before the interaction partner's stroke. These results support the hypothesis that the perception of the virtual player affects the online control of own actions.nonotspecifiedhttp://www.cyberneum.de/published-226The effect of visual information on motor control in social interaction tasks1501715422LeyrerLBKM2011_27MLeyrerSALinkenaugerHHBülthoffUKloosBMohlerNaples, FL, USA2011-09-006911th Annual Meeting of the Vision Sciences Society (VSS 2011)Newer technology is allowing for virtual environments to become more realistic by providing visual image quality that is very similar to that in the real world. Regardless, egocentric distances estimates in virtual reality have been shown to be underestimated (Thompson et al., 2004). Interestingly, this underestimation decreases after individuals view self-representing avatars in the virtual environment; especially when the avatars are self-animated (Mohler et al., 2010). These finding support perspectives on embodied perception which assert that the body and its action capabilities can act as a “perceptual ruler” that the perceiver uses to scale the world. To test this perspective, we immersed participants into a full-cue, virtual environment where they viewed a self-animated avatar from behind at a distance of 3.5 m away at the same eye-height as the avatar. We manipulated the relationship between the size of the avatar and the size of the virtual room (which included familiar objects) to see if participants would attribute these changes either to the size of the world or to the size of their body. Participants made verbal estimates about the size of self and the world and performed a walking-in-place task. We found that participants verbally attributed the apparent size difference to the virtual world and not to the self which suggests that space perception is grounded in the physical body. Further, we found an influence of condition on the post/pre walking-in-place drift suggesting that the participants felt embodied in the third person animated avatar. Further research needs to be conducted in order to fully understand the relative importance of visual cues about self, such as motion coupling, eye-height and distance of avatar from observer, on perception and action in virtual worlds.nonotspecifiedhttp://www.cyberneum.de/published-69The influence of a scaled third-person animated avatar on perception and action in virtual environments1501715422delaRosaGC20117Sde la RosaMAGieseCCurioToulouse, France2011-09-0015434th European Conference on Visual PerceptionAdapting to an emotional facial expression biases emotional judgments of an ambiguous facial expression away from the adapted facial expression. Previous studies examining emotional facial adaptation effects used static emotional facial expressions as adaptors. Since natural facial expressions are inherently dynamic, dynamic information might enhance the magnitude of the emotional facial expression adaptation effect. We tested this hypothesis by comparing emotional facial expression adaptation effects for static and dynamic facial expression adaptors. Stimuli were generated using a dynamic 3D morphable face model. We found adaptation effects of similar magnitude for dynamic and static adaptors. When rigid head motion was removed (leaving only non-rigid intrinsic facial motion cues), the adaptation effects with dynamic adaptors disappeared. These results obtained with a novel method for the synthesis of facial expression stimuli suggest that at least part of the cognitive representation of facial expressions is dynamic and depends on head motion.nonotspecifiedhttp://www.cyberneum.de/published-154The influence of dynamic and static adaptors on the magnitude of high-level aftereffects for dynamic facial expression1501715422LeeBAWB20117RKLeeIBülthoffRArmannCWallravenHHBülthoffNaples, FL, USA2011-09-0062611th Annual Meeting of the Vision Sciences Society (VSS 2011)race (the other-race effect or ORE) has been widely cited. Nevertheless, recognizing the identity of a face is a complex task among many others; hence it might be premature to conclude that own-race faces are always easier to
process. We investigated whether same-race faces still have a processing advantage over other-race faces when only ethnicity-related information is available to differentiate between faces. We morphed the ethnicity of 20 Caucasians and 20 Asians faces toward their other-race counterpart while keeping their idiosyncratic, identity-related features. Morphing was done at three levels (20%, 50%, and 80% toward the other race). The task for two groups of participants (25 Tübingen and 26 Seoul participants) was to report which face looks more Caucasian (or Asian) after looking at the original face and a morphed face sharing the same idiosyncratic features. Both faces were presented side by side on a computer monitor in one task and sequentially
in another task. Importantly, we found no evidence for an ORE in participants’ performance and no performance difference between Tübingen and Seoul participants. Both groups were equally good and equally fast at
comparing the ethnicity of two faces regardless of the task, the ethnicity of the faces and the question asked. However, we did find evidence that Seoul and Tübingen participants used different viewing strategies. By investigating their eye-movements in the sequential task, we found that the ethnicity of participants affected fixation durations on specific areas of the face, especially
the nose. Also, the type of questions asked and stimulus race altered the pattern of eye movements. These results suggest that although Caucasians and Asians were equally good at dealing with ethnicity information of both races, they might employ different viewing strategies.nonotspecifiedhttp://www.cyberneum.de/published-626The other-race effect is not ubiquitous1501715422EsinsBS20117JEsinsIBülthoffJSchultzNaples, FL, USA2011-09-0067311th Annual Meeting of the Vision Sciences Society (VSS 2011)An important aspect of face recognition involves the role of featural and configurational information for face perception (e.g. Tanaka and Farah, 1993; Yovel and Duchaine, 2006; Rotshtein et al, 2007). In our study, we investigated the influence of featural and configural information on perceived similarity between faces. Eight pairs of male faces were chosen from our digital face database (http://faces.kyb.tuebingen.mpg.de). The texture and the face shape for both faces in a pair were equalized to create 2 basis faces that differed only in their inner facial features and their configuration, but not in face shape or texture. A computer algorithm allowed to parametrically morph the features, the configuration, or both between the two basis faces of a pair. In our case the morphing was done in 25% steps. 24 participants rated the similarity between pairs of the created faces using a 7-point Likert scale. The faces to compare came from the same basis face pair and could differ either in features or in configuration by 0%, 25%, 50%, 75% or 100%. The results revealed that for the same amount of morphing, faces differing by their features are perceived as less similar than faces differing by their configurations. These findings replicate previous results obtained with less natural or less controlled conditions. Furthermore, we found that linear increases of the difference between both faces in configural or featural information resulted in a nonlinear increase of perceived dissimilarity. An important aspect for the relevance of our results is how natural the face stimuli look like. We asked 24 participants to rate the naturalness of all stimuli including the original faces and the created faces. Despite numerous manipulations, the vast majority of our created face stimuli were rated as natural as the original faces.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/VSS-2011-Esins.pdfpublished-673The role of featural and configural information for perceived similarity between faces1501715422KaulardFBS20117KKaulardALFernandez CruzHHBülthoffJSchultzNaples, FL, USA2011-09-0060511th Annual Meeting of the Vision Sciences Society (VSS 2011)Facial expressions convey both emotional and conversational signals. Research focuses mostly on EMOTIONAL expressions and consistenly finds that these can be reliably distinguished along at least two dimensions: valence and arousal. CONVERSATIONAL expressions, i.e. those conveying mainly communicative meaning, are thought to be less emotional laden. Interestingly, we found evidence pointing towards the same first two underlying dimensions for CONVERSATIONAL expressions when presented dynamically. The question now arises: "Is the emergence of the valence and arousal dimensions for conversational facial expressions based on the emotional content of these expressions?" To answer this, we used questions addressing the emotional (Fontaine et al, 2007) and the conversational content separately. If the distinction of conversational expressions is based on the small amount of emotional information they might contain, we expect emotional content questions to allow a separation of those expressions. Ten native German participants answered a set of 27 questions for 6 emotional and 6 conversational expressions, both presented statically and dynamically, using a rating scale. A dissimilarity matrix was computed for the expressions. To uncover the meaning of the first two underlying dimensions allowing expression differentiation, multidimensional scaling (MDS) was used. Our results show that static and dynamic emotional expressions can only be distinguished by means of emotional content questions. For these emotional expressions, the valence and arousal dimensions emerged in the MDS. In contrast, conversational expressions can be distinguished using conversational content questions but not using emotional content questions. Unlike emotional expressions, dynamic information improved distinction of conversational expressions substantially. We found evidence for valence and arousal to be the underlying dimensions for conversational expressions. Our results suggest that the distinction of conversational expressions along the first two dimensions is based on conversational rather than emotional content. Moreover, different types of facial expressions benefit to different degrees from dynamic information.nonotspecifiedhttp://www.cyberneum.de/published-605Uncovering the principles that allow a distinction of conversational facial expressions1501715422BulthoffSMT20117IBülthoffSShrimptonBJMohlerIMThorntonNaples, FL, USA2011-09-0059611th Annual Meeting of the Vision Sciences Society (VSS 2011)In a previous series of desktop experiments we found no evidence that individuals' height influenced their representation of others' faces or their ability to process faces viewed from above or below (VSS 2009). However, in those experiments face orientation and body height were ambiguous as isolated faces were shown on a computer screen to an observer sitting on a chair. To address those concerns and to specifically examine the influence of learned viewpoint, we created a virtual museum containing 20 full-bodied avatars (statues) that were either sitting or standing. Using a head-mounted display, observers walked through this virtual space three times, approached each statue and viewed them from any horizontal (yaw) angle without time restrictions. We equated eye-level - and thus simulated height – for all participants and restricted their vertical movement to ensure that the faces of sitting avatars were always viewed from above and standing avatars from below. After familiarization, recognition was tested using a standard old-new paradigm in which 2D images of the learnt faces were shown from various viewpoints. Results showed a clear influence of learned viewpoint. Faces that had been learned from above (below) were recognized more quickly and accurately in that orientation than from the opposite orientation. Thus, recognition of specific, newly learned faces appears to be view-dependent in terms of pitch angle. Our failure to find a height effect in our previous study suggests that the variety of views of human faces experienced during a lifetime and possibly the preponderance of conversational situations between humans at close range typically counteracts any influence that body size might have on a person's viewing experience of others' faces.nonotspecifiedhttp://www.cyberneum.de/published-596Using avatars to explore height/pitch effects when
learning new faces1501715422LinkenaugerMB20117SALinkenaugerBJMohlerHHBülthoffNaples, FL, USA2011-09-007011th Annual Meeting of the Vision Sciences Society (VSS 2011)According to the functional approach to the perception of spatial layout, angular optic variables that indicate extents are scaled to the action capabilities of the body (see Proffitt, 2006, POPS, for a review). For example, reachable extents are perceived as a proportion of the maximum extent to which one can reach, and the apparent sizes of graspable objects are perceived as a proportion of the maximum extent that one can grasp (Linkenauger et al., 2009, JEP:HPP; Linkenauger, Ramenzoni, & Proffitt, 2010, Psychol Sci; Witt, Proffitt, & Epstein, 2005, JEP:HPP). Therefore, apparent distances and sizes can be influenced by changing the action capabilities of the body. In order to directly manipulate the perceived action capabilities of the body, participants were immersed into a full cue virtual environment. In real time, participants' hand, arm, and head movements were mapped onto a self-avatar which the participant viewed from the first-person perspective via a head-mounted display. To manipulate perceived action capabilities, the apparent size of the participants' hand was altered by decreasing or increasing the size of the self-avatar's virtual hand (small, normal, and large). Participants estimated the sizes of various objects in the virtual environment. Participants perceived objects to be larger when their virtual hand was smaller and perceived objects to be smaller when their virtual hand was larger. Consistent with the functional approach, the differences in apparent size across the conditions increased as a function of object size, suggesting changes in the scaling metric rather than a constant bias.nonotspecifiedhttp://www.cyberneum.de/published-70Welcome to Wonderland: The Apparent Size of the Body Influences Perceived Extents in Virtual Environments1501715422KaularddSFBW20117KKaulardSde la RosaJSchultzALFernandez CruzHHBülthoffCWallravenToulouse, France2011-09-0011534th European Conference on Visual PerceptionSimilarity ratings are used to investigate the cognitive representation of facial expressions. The perceptual and cognitive properties (eg physical aspects, motor expressions, action tendencies) driving the similarity judgments of facial expressions are largely unknown. We examined potentially important properties with 27 questions addressing the emotional and conversational content of expressions (semantic differential). The ratings of these semantic differentials were used as predictors for facial expression similarity ratings. The semantic differential and similarity-rating task were performed on the same set of facial expression videos: 6 types of emotional (eg happy) and 6 types of conversational (eg don’t understand) expressions. Different sets of participants performed the two tasks. Multiple regression was used to predict the similarity data from the semantic differential questions. The best model for emotional expressions consisted of two emotional questions explaining 75% of the variation in similarity ratings. The same model explained significantly less variation for conversational expressions (38%). The best model for those expressions consisted of a single conversational question explaining 44% of the variation. This study shows which properties of facial expressions might affect their perceived similarity. Moreover, our results suggest that different perceptual and cognitive properties might underlie similarity judgments about emotional and conversational expressions.nonotspecifiedhttp://www.cyberneum.de/published-115What are the properties underlying similarity judgments of facial expressions?1501715422SchultzBP20117JSchultzMBrockhausKPilzToulouse, France2011-09-0011634th European Conference on Visual PerceptionVisual perception of moving faces activates parts of the human superior temporal sulcus (STS) whereas static facial information is mainly processed in areas of ventral temporal and lateral occipital cortex. However, recent findings show that the latter regions also respond more to moving faces than to static faces. Here, we investigated the origin of this activation increase, considering the following causes: (i) facial motion per se, (ii) increased static information due to the higher number of frames constituting the movie stimuli, and/or (iii) increased attention towards moving faces. We presented non-rigidly moving faces to subjects in an fMRI scanner. We manipulated static face information and motion fluidity by presenting ordered and scrambled sequences of frames at the original or reduced temporal resolutions. Subjects performed a detection task unrelated to the face stimuli in order to equate attentional influences. Results confirm the increased response due to facial motion in the face-sensitive temporal regions. Activation generally increased with the number of frames but decreased when frames were scrambled. These results indicate that the activation increase induced by moving faces is due to smooth, natural motion and not only to increased static information or attentional modulation.nonotspecifiedhttp://www.cyberneum.de/published-116What human brain regions like about moving faces?1501715422SecchiRF201110CSecchiPRobuffo GiordanoAFranchiThorntonCMB201110IMThorntonFCanairdPMamassianHHBülthoffLinkenaugerMB2011_210SLinkenaugerBJMohlerHHBülthoffChuang201110LChuangBulthoff2011_410HHBülthoffCunninghamIS201128DCunninghamTIsenbergSNSpencer56433TMeilingerJMWienerABerthoz2011-08-0063910421054Memory & CognitionThe integration of spatial information perceived from different viewpoints is a frequent, yet largely unexplored, cognitive ability. In two experiments, participants saw two presentations, each consisting of three targets—that is, illuminated tiles on the floor—before walking the shortest possible path across all targets. In Experiment 1, participants viewed the targets either from the same viewpoint or from different viewpoints. Errors in recalling targets increased if participants changed their viewpoints between presentations, suggesting that memory acquired from different viewpoints had to be aligned for integration. Furthermore, the error pattern indicates that memory for the first presentation was transformed into the reference frame of the second presentation. In Experiment 2, we examined whether this transformation occurred because new information was integrated already during encoding or because memorized information was integrated when required. Results suggest that the latter is the case. This might serve as a strategy for avoiding additional alignments.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/Memory-Cognition-2011-Meilinger.pdfpublished12The integration of spatial information across different viewpoints1501715422CaniardBMLT20117FCaniardHHBülthoffPMamassianS-WLeeIMThorntonToulouse, France2011-08-001011088th Symposium on Applied Perception in Graphics and Visualization (APGV 2011)When the sine-wave grating of a Gabor patch drifts to the left or right, the perceived position of the entire object is shifted in the direction of local motion. In the current paper, we explored whether active control of the physical position of the patch can overcome such motion induced illusory displacement. We created a simple computer game and asked participants to continuously guide a Gabor
patch along a randomly curving path. When the grating inside
the Gabor patch was stationary, participants could perform this task without error. When the grating drifted to either left or right, we observed systematic errors consistent with previous reports of motion-induced illusory displacement. Specifically, when the grating drifted to the right, participants adjusted the global position of the patch to the left of the target line, and when it drifted to the left, errors were to the right of the line. The magnitude of the errors was consistent with previously reported perceptual judgements for centrally presented items, and scaled systematically with the speed of local drift. Importantly, we found no evidence that participants
could adapt or compensate for illusory displacement given active control of the target. The current findings could have important implications for interface design, suggesting that local dynamic components of a display could affect perception and action within the more global application environment.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/APGV-2011-caniard.pdfpublished7Active control does not eliminate motion-induced illusory displacement1501715422AlaimoPB2011_27SAlaimoLPolliniHHBülthoffPortland, OR, USA2011-08-001937AIAA Modeling and Simulation Technologies Conference 2011The paper focuses on the implementation of an admittance based control scheme in a bilateral teleoperation set-up for an Unmanned Aerial Vehicle (UAV) under time delay. The goal of this study is to assess and improve the stability characteristics of the bilateral teleoperator. Computer simulations were conducted to evaluate the effectiveness of the admittance-based control scheme. A commercial impedance-like haptic device was chosen to simulate the control stick: the master device. The slave system is constituted by the dynamics of the aircraft under control; in order to maximize the pilot attention on its task, only the lateral aircraft dynamics was considered. A virtual environment was displayed during the experiments to produce the visual cues. In order to evaluate the system, we prepared a control task where the aircraft had to be flown in a virtual urban canyon with buildings placed irregularly (non Manhattan-like) along the desired path by avoiding the collisions with them. A repulsive force field was associated to the obstacles and a force was sent back to the operator through the communication link. A compensator capable of flying autonomously the aircraft through the buildings with satisfactory performance was designed first using linear techniques then the haptic augmentation system was derived from the compensator by splitting it in two parts: the actual haptic cueing for the pilot and the simulated the pilot effort. The latter component was used only for the preliminary assessment of the system and was removed in simulations where a real pilot operated the stick (the master device). Experimental results and analytical motivations as well have shown that a haptic force which is simply proportional to the distance from the obstacles cannot stabilize the system: a relevant anticipatory effect or phase lead (as the derivative effect of standard industrial controllers) is needed. In order to manage the degradation of performance and overall stability when a delay is present in the communication paths, an admittance-based controller was designed together with an observer for the force generated by the human operator on the stick. The admittance-based Force Position teleoperation scheme was shown by simulations and tests with real pilots to improve the performance of the system under consideration.nonotspecifiedhttp://www.cyberneum.de/published18Admittance-Based Bilateral Teleoperation with Time Delay for an Unmanned Aerial Vehicle involved in an Obstacle Avoidance Task1501715422AlaimoPB20117SAlaimoLPolliniJPBrescianiHHBülthoffPortland, OR, USA2011-08-00732749AIAA Modeling and Simulation Technologies Conference 2011This paper focuses on a novel concept of haptic cueing developed in order to optimize the performance of an Unmanned Aerial Vehicle (UAV) teleoperator and to improve the human-machine interfaces in a mixed obstacle avoidance/wind gust rejection task. It presents an experimental evaluation of two different Haptic aiding concepts: one based on what we called Direct Haptic Aiding (DHA) approach, and a novel one based on the Indirect Haptic Aiding (IHA) approach. The two haptic aids were compared with a baseline condition in which no haptic force was associated to the obstacles (NoEF condition). It will be shown that IHA-based approach definitely improves the pilots¡¯ performance with respect to the other approaches. A significant difference in performance (i.e. the number of collisions) was noticed between IHA and both DHA and NoEF conditions. The goal of this paper is to show that the IHA philosophy is a valid alternative to the other commonly used, and published in the scientific literature, approaches which fall in the DHA category.nonotspecifiedhttp://www.cyberneum.de/published17Experiments of Direct and Indirect Haptic Aiding for Remotely Piloted Vehicles with a Mixed Wind Gust Rejection/Obstacle Avoidance Task1501715422McManusBSdBM20117EAMcManusBBodenheimerSStreuberSde la RosaHHBülthoffBJMohlerToulouse, France2011-08-0037448th Symposium on Applied Perception in Graphics and Visualization (APGV 2011)Humans have been shown to perceive and perform actions differently in immersive virtual environments (VEs) as compared to the real world. Immersive VEs often lack the presence of virtual characters; users are rarely presented with a representation of their own body and have little to no experience with other human avatars/characters. However, virtual characters and avatars are more often being used in immersive VEs. In a two-phase experiment, we investigated the impact of seeing an animated character or a self-avatar in a head-mounted display VE on task performance. In particular, we examined performance on three different behavioral tasks in the VE. In a learning phase, participants either saw a character animation or an animation of a cone. In the task performance phase, we varied whether participants saw a co-located animated self-avatar. Participants performed a distance estimation, an object interaction and a stepping stone locomotion task within the VE. We find no impact of a character animation or a self-avatar on distance estimates. We find that both the animation and the self-avatar influenced task performance which involved interaction with elements in the environment; the object interaction and the stepping stone tasks. Overall the participants performed the tasks faster and more accurately when they either had a self-avatar or saw a character animation. The results suggest that including character animations or self-avatars before or during task execution is beneficial to performance on some common interaction tasks within the VE. Finally, we see that in all cases (even without seeing a character or self-avatar animation) participants learned to perform the tasks more quickly and/or more accurately over time.nonotspecifiedhttp://www.cyberneum.de/published7The influence of avatar (self and character) animations on distance estimation, object interaction and locomotion in immersive virtual environments1501715422LeyrerLBKM20117MLeyrerSALinkenaugerHHBülthoffUKloosBMohlerToulouse, France2011-08-0067748th Symposium on Applied Perception in Graphics and Visualization (APGV 2011)It is well known that eye height is an important visual cue in the perception of apparent sizes and affordances in virtual environments. However, the influence of visual eye height on egocentric distances in virtual environments has received less attention. To explore this influence, we conducted an experiment where we manipulated the virtual eye height of the user in a head-mounted display virtual environment. As a measurement we asked the participants to verbally judge egocentric distances and to give verbal estimates of the dimensions of the virtual room. In addition, we provided the participants a self-animated avatar to investigate if this virtual self-representation has an impact on the accuracy of verbal distance judgments, as recently evidenced for distance judgments accessed with an action-based measure. When controlled for ownership, the avatar had a significant influence on the verbal estimates of egocentric distances as found in previous research. Interestingly, we found that the manipulation of eye height has a significant influence on the verbal estimates of both egocentric distances and the dimensions of the room. We discuss the implications which these research results have on those interested in space perception in both immersive virtual environments and the real world.nonotspecifiedhttp://www.cyberneum.de/published7The influence of eye height and avatars on egocentric distance estimates in immersive virtual environments1501715422NieuwenhuizenMvB20117FMNieuwenhuizenMMulderMMvan PaassenHHBülthoffPortland, OR, USA2011-08-00204218AIAA Modeling and Simulation Technologies Conference 2011Full flight simulators are widely being used for training of pilots as they provide a cost-effective alternative over aircraft. However, a compromise must always be found between
the amount of motion cueing that needs to be presented to the pilot for effective training and the available workspace of the simulator. In literature, contradictory reports are found on the effect of motion cues on pilot performance in the simulator. In this paper, the results are presented of an experiment in which the influence of the quality of motion systems was investigated. A model of the MPI Stewart platform was simulated on the SIMONA Research Simulator and the motion system characteristics of both simulators were varied systematically to determine their effects on pilot control behaviour. The time
delay and noise characteristics of the simulators did not have an effect in this experimental task. However, it was found that the bandwidth of the motion system had a significant effect on performance and control behaviour. Results indicate that the motion cues were barely used at all in conditions with a low bandwidth, and that participants relied on the visual cues to generate lead needed in their control task.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/AIAA-2011-6321-Nieuwenhuizen.pdfpublished14The Influence of Motion System Characteristics on Pilot Control Behaviour1501715422Bulthoff2011_510HHBülthoffBulthoff2011_310HHBülthoff67893AReichenbachJ-PBrescianiAPeerHHBülthoffAThielscher2011-07-0072116021612Cerebral CortexThe posterior parietal cortex (PPC) plays an important role in controlling voluntary movements by continuously integrating sensory information about body state and the environment. We tested which subregions of the PPC contribute to the processing of target- and body-related visual information while reaching for an object, using a reaching paradigm with 2 types of visual perturbation: displacement of the visual target and displacement of the visual feedback about the hand position. Initially, functional magnetic resonance imaging (fMRI) was used to localize putative target areas involved in online corrections of movements in response to perturbations. The causal contribution of these areas to online correction was tested in subsequent neuronavigated transcranial magnetic stimulation (TMS) experiments. Robust TMS effects occurred at distinct anatomical sites along the anterior intraparietal sulcus (aIPS) and the anterior part of the supramarginal gyrus for both perturbations. TMS over neighboring sites did not affect online control. Our results support the hypothesis that the aIPS is more generally involved in visually guided control of movements, independent of body effectors and nature of the visual information. Furthermore, they suggest that the human network of PPC subregions controlling goal-directed visuomotor processes extends more inferiorly than previously thought. Our results also point toward a good spatial specificity of the TMS effects.nonotspecifiedhttp://www.cyberneum.de//fileadmin/user_upload/files/publications/Cerebral-Cortex-2010-Reichenbach_6789[0].pdfpublished10Contributions of the PPC to online control of visually guided reaching movements assessed with fMRI-guided TMS1501715422150171882164553HISonTBhattacharjeeHHashimoto2011-07-00112515771601Advanced RoboticsThere is generally a tradeoff between stability and performance in haptic control systems. Teleoperation systems with haptic feedback are no exception. Scaling in these systems used in applications such as telemicrosurgical systems has further effects on the stability and performance. This paper focuses on those applications interacting with soft tissues and analyzes the effects of the scaling in an effort to increase the performance of these systems while maintaining the stability. Position tracking and kinesthetic perception are especially important in the tele-surgical systems and, hence, are used as the performance criteria. Quantitatively defined stability robustness, which is based on Llewellyn's absolute stability criterion, is used as a metric for stability analysis. Various choices of scaling factors, and human and environment impedances are then investigated. The proposed kinesthetic perception concept is validated using psychophysical experiments. Widely used bilateral control architectures such as the two-channel position-position, two-channel force-position and four-channel controls are specifically analyzed and evaluated using simulations and experiments with phantom soft tissues. Results also show that the force-position control architecture shows the best position tracking performance irrespective of the scaling factors while the four-channel controller shows the best kinesthetic perception capability.nonotspecifiedhttp://www.cyberneum.de/published24Effect of Scaling on the Performance and Stability of Teleoperation Systems Interacting with Soft Environments1501715422FrissenCSE20113IFrissenJLCamposJLSoumanMOErnst2011-07-002212163176Experimental Brain ResearchSpatial updating during self-motion typically involves the appropriate integration of both visual and non-visual cues, including vestibular and proprioceptive information. Here, we investigated how human observers combine these two non-visual cues during full-stride curvilinear walking. To obtain a continuous, real-time estimate of perceived position, observers were asked to continuously point toward a previously viewed target in the absence of vision. They did so while moving on a large circular treadmill under various movement conditions. Two conditions were designed to evaluate spatial updating when information was largely limited to either proprioceptive information (walking in place) or vestibular information (passive movement). A third condition evaluated updating when both sources of information were available (walking through space) and were either congruent or in conflict. During both the passive movement condition and while walking through space, the pattern of pointing behavior demonstrated evidence of accurate egocentric updating. In contrast, when walking in place, perceived self-motion was underestimated and participants always adjusted the pointer at a constant rate, irrespective of changes in the rate at which the participant moved relative to the target. The results are discussed in relation to the maximum likelihood estimation model of sensory integration. They show that when the two cues were congruent, estimates were combined, such that the variance of the adjustments was generally reduced. Results also suggest that when conflicts were introduced between the vestibular and proprioceptive cues, spatial updating was based on a weighted average of the two inputs.nonotspecifiedhttp://www.cyberneum.de/published13Integration of vestibular and proprioceptive signals for spatial updating15017154221501718824Franchi20117AFranchiLos Angeles, CA, USA2011-07-00112RSS 2011 Workshop “3D Exploration, Mapping, and Surveillance with Aerial Robots”This talk will present some recent theoretical and experimental results in the relatively new topic of Bilateral Aerial Teleoperation of Multiple UAVs. In this non-conventional teleoperation field a human operator partially controls the behavior of a semi-autonomous swarm of UAVs by means of one or more haptic interfaces, and receives back a force cue which is informative both of the swarm tracking performance and of some relevant properties of the surrounding environment (e.g., presence of obstacles or other threats). This kind of systems are designed in order to enhance the telepresence of the operator and the quality of the human robot interaction, especially when applied to practical scenarios, like search and rescue, surveillance, exploration and mapping. In particular, the focus of the talk will be on the design of a stable bilateral interconnection between the user and the swarm of UAVs, considered as a deformable object with a given shape (top-down approach) to be achieved with suitable formation control algorithms using either distance-only or bearing-only sensors.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/RSS-2011-Workshop-Franchi.pdfpublished11Decentralized Bilateral Aerial Teleoperation of Multiple UAVs - Part II: a Top-down Perspective1501715422RobuffoGiordano2011_27PRobuffo GiordanoLos Angeles, CA, USA2011-07-00111RSS 2011 Workshop “3D Exploration, Mapping, and Surveillance with Aerial Robots”In this talk, we will review some recent advancements in the field of Aerial Teleoperation, i.e., how to bilaterally
couple a single human operator with a remote fleet of semiautonomous UAVs which 1) must keep some spatial formation and avoid inter- and obstacle- collisions, and 2) must collectively follow the human commands. The emphasis will be placed on the modeling and control tools needed for establishing such a non-conventional bilateral channel: in particular, we will study how to render the multi-UAV “slave side” a passive system w.r.t. the environment, and how to still enforce global connectivity maintenance despite limited sensing and loss of visibility because
of occlusions.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/RSS-2011-Workshop-Robuffo-1.pdfpublished10Decentralized Bilateral Aerial Teleoperation of Multiple UAVs – Part I: a Bottom-up Perspective1501715422HensonMBM20117AHensonHAMallotHHBülthoffTMeilingerBoston, MA, USA2011-07-002764276933rd Annual Meeting of the Cognitive Science Society (CogSci 2011)The present study examined whether spatial information of a
novel environment was integrated within a reference frame
during initial learning, or only later when required for pointing to other targets. Twenty-two participants repeatedly walked through a multi-corridor virtual environment, presented via a head-mounted display. At several stages within the learning process they were teleported to locations along the route and asked to self-localize and point to other locations. Pointing was
faster during later tests as well as for closer targets, both of which might require less integration. Participants tested only after extended exposure (late pointers) took longer than participants who had received testing interspersed throughout the same amount of exposure (early pointers). Pointing latency did not differ between groups when comparing performance on their first pointing test, despite vastly different exposure. These results are inconsistent with the assumption that participants
already integrated spatial information within a single reference frame during learning and simply accessed this information during testing. Rather, spatial integration is a time consuming process which is not necessarily undertaken if not required.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/CogSci-2011-Henson.pdfpublished5When do we integrate spatial information acquired by walking through environmental spaces?1501715422Breidt2011_210MBreidtThorntonCMB2011_210IMThorntonFCaniardPMamassianHHBülthoffBulthoffAWB201110RKLeeIBülthoffRArmannCWallravenHHBülthoffBulthoff2011_1010IBülthoffBulthoff2011_210HHBülthoffDodds201110TJDoddsBJMohlerHHBülthoffLinkenauger201010SLinkenaugerMeilinger2011_210TMeilinger59233MDi LucaBKnörleinMOErnstMHarders2011-06-00585245259Brain Research BulletinSpring compliance is perceived by combining the sensed force exerted by the spring with the displacement caused by the action (sensed through vision and proprioception). We investigated the effect of delay of visual and force information with respect to proprioception to understand how visual–haptic perception of compliance is achieved. First, we confirm an earlier result that force delay increases perceived compliance. Furthermore, we find that perceived compliance decreases with a delay in the visual information. These effects of delay on perceived compliance would not be present if the perceptual system would utilize all force–displacement information available during the interaction. Both delays generate a bias in compliance which is opposite in the loading and unloading phases of the interaction. To explain these findings, we propose that information during the loading phase of the spring displacement is weighted more than information obtained during unloading. We confirm this hypothesis by showing that sensitivity to compliance during loading movements is much higher than during unloading movements. Moreover, we show that visual and proprioceptive information about the hand position are used for compliance perception depending on the sensitivity to compliance. Finally, by analyzing participants’ movements we show that these two factors (loading/unloading and reliability) account for the change in perceived compliance due to visual and force delays.nonotspecifiedhttp://www.cyberneum.de/published14Effects of visual–haptic asynchronies and loading–unloading movements on compliance perception15017154221501718824FlemingJM20113RWFlemingFJäkelLTMaloney2011-06-00622812820Psychological ScienceUnder typical viewing conditions, human observers readily distinguish between materials such as silk, marmalade, or granite, an achievement of the visual system that is poorly understood. Recognizing transparent materials is especially challenging. Previous work on the perception of transparency has focused on objects composed of flat, infinitely thin filters. In the experiments reported here, we considered thick transparent objects, such as ice cubes, which are irregular in shape and can vary in refractive index. An important part of the visual evidence signaling the presence of such objects is distortions in the perceived shape of other objects in the scene. We propose a new class of visual cues derived from the distortion field induced by thick transparent objects, and we provide experimental evidence that cues arising from the distortion field predict both the successes and the failures of human perception in judging refractive indices.nonotspecifiedhttp://www.cyberneum.de/published8Visual Perception of Thick Transparent Materials1501715422RuddleVB20113RARuddleEVolkovaHHBülthoff2011-06-002:1018122ACM Transactions on Computer-Human InteractionThis study investigated the effect of body-based information (proprioception, etc.) when participants navigated large-scale virtual marketplaces that were either small (Experiment 1) or large in extent (Experiment 2). Extent refers to the size of an environment, whereas scale refers to whether people have to travel through an environment to see the detail necessary for navigation. Each participant was provided with full body-based information (walking through the virtual marketplaces in a large tracking hall or on an omnidirectional treadmill), just the translational component of body-based information (walking on a linear treadmill, but turning with a joystick), just the rotational component (physically turning but using a joystick to translate) or no body-based information (joysticks to translate and rotate). In large and small environments translational body-based information significantly improved the accuracy of participants' cognitive maps, measured using estimates of direction and relative straight line distance but, on its own, rotational body-based information had no effect. In environments of small extent, full body-based information also improved participants' navigational performance. The experiments show that locomotion devices such as linear treadmills would bring substantial benefits to virtual environment applications where large spaces are navigated, and theories of human navigation need to reconsider the contribution made by body-based information, and distinguish between environmental scale and extent.nonotspecifiedhttp://www.cyberneum.de/published21Walking improves your cognitive map in environments that are large-scale and large in extent1501715422SonKCFRLB20117HISonJKimLLChuangAFranchiPRobuffo GiordanoDLeeHHBülthoffIstanbul, Turkey2011-06-00149154IEEE 2011 World Haptics Conference (WHC 2011)The use of multiple unmanned aerial vehicles (UAVs) is increasingly being incorporated into a wide range of teleoperation applications. To date, relevant research has largely been focused on the development of appropriate control schemes. In this paper, we extend previous research by investigating how control performance could be improved by providing the teleoperator with haptic feedback cues. First, we describe a control scheme that allows a teleoperator to manipulate the flight of multiple UAVs in a remote environment. Next, we present three designs of haptic cue feedback that could increase the teleoperator's environmental awareness of such a remote environment. These cues are based on the UAVs' i) velocity information, ii) proximity to obstacles, and iii) a combination of these two sources of information. Finally, we present an experimental evaluation of these haptic cue designs. Our evaluation is based on the teleoperator's perceptual sensitivity to the physical environment inhabited by the multiple UAVs. We conclude that a teleoperator's perceptual sensitivity is best served by haptic feedback cues that are based on the velocity information of multiple UAVs.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/WHC-2011-Son.pdfpublished5An Evaluation of Haptic Cues on the Tele-Operator's Perceptual Awareness of Multiple UAVs' Environments1501715422RobuffoGiordanoFSB20117PRobuffo GiordanoAFranchiCSecchiHHBülthoffLos Angeles, CA, USA2011-06-002732802011 Robotics: Science and Systems ConferenceIn this paper, we present a decentralized passivity-based control strategy for the bilateral teleoperation of a group of Unmanned Aerial Vehicles (UAVs). The human operator at the master side can command the group motion and receive suitable force cues informative about the remote environment. By properly controlling the energy exchanged within the slave side (the UAV group), we guarantee that the connectivity of the group is preserved and we prevent inter-agent and obstacle collisions. At the same time, we allow the behavior of the UAVs to be as flexible as possible with arbitrary split and join maneuvers. The results of the paper are validated by means of human/hardware-in-the-loop (HHIL) simulations.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/RSS-2011-Robuffo.pdfpublished7Bilateral Teleoperation of Groups of UAVs with Decentralized Connectivity Maintenance1501715422GaissertW20117NGaissertCWallravenIstanbul, Turkey2011-06-00451456IEEE World Haptics Conference (WHC 2011)In this study we want to address the question to what extent the visual and the haptic modalities contribute to the final formation of a complex multisensory perceptual space. By varying three shape parameters a physical shape space of shell-like objects was generated. Participants were allowed to either see or touch the objects or use both senses to explore the objects. Similarity ratings were performed and analyzed using multidimensional scaling (MDS) techniques. By comparing the unimodal perceptual spaces to the multimodal perceptual space we tried to resolve the impact of the visual and the haptic modalities on the combined percept. We found that neither the visual nor the haptic modality dominated the final percept, but rather that the two modalities contributed to the combined percept almost equally. To investigate to which degree these results are transferrable to natural objects, we performed the same visual, haptic, and visuo-haptic similarity ratings and multidimensional scaling analyses using a set of natural sea shells. Again, we found almost equal contributions of the visual and the haptic modalities to the combined percept. Our results suggest that multisensory perceptual spaces are based on a complex combination of object information gathered by different senses.nonotspecifiedhttp://www.cyberneum.de/published5Integrating Visual and Haptic Shape Information to Form a Multimodal Perceptual Space1501715422JumpPWFZSSBDSHNB20117MJumpGDPadfieldMDWhiteDFloreanoPFuaJ-CZuffereyFSchillRSiegwartSBouabdallahMDeckerJSchipplMHöfingerHHBülthoffFMNieuwenhuizenLondon, UK2011-06-00169195Royal Aeronautical Society Conference on the Future Rotorcraft (RAeS 2011)This paper describes the European Commission Framework 7 funded project myCopter (2011-2014). The project is still at an early stage so the paper starts with the current transportation issues faced by developed countries and describes a means to solve them through the use of personal aerial transportation. The concept of personal air vehicles (PAV) is briefly reviewed and how this project intends to tackle the problem from a different perspective described. It is argued that the key reason that many PAV concepts have failed is because the operational infrastructure and socio-economic issues have not been properly addressed; rather, the start point has been the design of the vehicle itself. Some of the key aspects that would make a personal aerial transport system (PATS) viable include the required infrastructure and associated technologies, the skill levels and machine interfaces needed by the occupant or pilot and the views of society as a whole on the acceptability of such a proposition. The myCopter project will use these areas to explore the viability of PAVs within a PATS. The paper provides an overview of the project structure, the roles of the partners, and hence the available research resources, and some of the early thinking on each of the key project topic areas.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/RAeS-Spring-2011-Nieuwenhuizen.pdfpublished26myCopter: Enabling Technologies for Personal Air Transport Systems1501715422EngelC2011_27DEngelCCurioBaden-Baden, Germany2011-06-00429435IEEE Intelligent Vehicles Symposium (IV 2011)How likely is it that a driver notices a person standing on the side of the road? In this paper we introduce the concept of pedestrian detectability. It is a measure of how probable it is that a human observer perceives pedestrians in an image. We acquire a dataset of pedestrians with their associated detectabilities in a rapid detection experiment using images of street scenes. On this dataset we learn a regression function that allows us to predict human detectabilities from an optimized set of image and contextual features. We exploit this function to infer the optimal focus of attention for pedestrian detection. With this combination of human perception and machine vision we propose a method we deem useful for the optimization of Human-Machine-Interfaces in driver assistance systems.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/IV-2011-Engel.pdfpublished6Pedestrian Detectability: Predicting Human Perception Performance with Machine Vision1501715422ReichenbachBBT20117AReichenbachJ-PBrescianiHHBülthoffAThielscherQuébec City, Canada2011-06-0017th Annual Meeting of the Organization for Human Brain Mapping (HBM 2011)fMRI and TMS studies have shown that visual and proprioceptive information for motor control are integrated in the posterior parietal cortex (PPC) (e.g. Culham and Valyear, 2006; Filimon et al., 2009; Reichenbach et al., 2010). When the head is moving in space during a goal-directed movement, vestibular signals have to be integrated into the motor processing as well. The neural correlates of these integration processes during motor control have not been investigated thus far. However, fMRI studies about vestibular stimulation have shown that the PPC is also processing vestibular information (Suzuki et al., 2001; Dieterich et al., 2003; Stephan et al., 2005). Furthermore, Seemungal et al. (2008) demonstrated that the administration of TMS over the PPC disturbs the perception of the position in space when the body is rotated. For the TMS study presented here, we used the behavioral paradigm of Bresciani et al. (2002) where subjects performed a goal-directed reaching task while suddenly being rotated. In order to assess the neural correlates of vestibular information processing for movement control, we probed with TMS the necessity of several sites on the PPC for this motor task.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/HBM-2011-Reichenbach.pdfpublished0Role of the PPC in vestibular information processing during goal-directed movements tested with TMS15017154221501718821GianiOBKPN20117ASGianiEBOrtizPBelardinelliMKleinerHPreisslUNoppeneyQuébec City, Canada2011-06-0017th Annual Meeting of the Organization for Human Brain Mapping (HBM 2011)How does the brain integrate information within and across sensory modalities to form a unified percept? This question has previously been addressed using transient stimuli, analyzed in the time domain. Alternatively, sensory interactions can be investigated using frequency analyses of steady state responses (SSRs). SSRs are elicited by periodic sensory stimulation (such as frequency modulated tones). In the frequency domain, 'true' signal integration is reflected by non-linear crossmodulation terms (i.e. the sums and differences of the individual SSR frequencies). In addition, two signals may modulate the amplitude of the fundamental and harmonic frequencies of one another. Using visual (V) and auditory (A) SSRs, we investigated whether A and V signals are truly integrated as indexed by crossmodulation terms or simply modulate the expression of each other's dominant frequencies. To manipulate perceptual synchrony, we imposed additional slow modulations on the auditory and visual SSRs either at same or different frequencies. This also enabled us to investigate the integration of two dynamic features within one sensory modality.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/HBM-2011-Giani.pdfpublished0Using steady state responses in MEG to study information integration within and across the senses15017154221501718826Volkova201110EPVolkovaCurio2011_210CCurioWelchmanMBF20117AWelchmanAMuryyHBanRFlemingCardiff, UK2011-05-26AVA/BMVA Spring Meeting 2011 (AGM)Successful behaviour relies on reliable estimates of the three-dimensional structure of the environment, facilitating recognition and interaction. Here we review recent work that seeks to understand the neural mechanisms that achieve 3D vision. We focus on the perceptual use of binocular disparity – considering both the computational principles that guide perception and the neural implementation that achieves it. First, we cover work that examines the disparities produced when viewing reflective (specular) objects binocularly. Typically, this produces a considerable discrepancy between the distance specified by disparity (the adanaclastic surface) and the physical surface of the object. We measure perceptual judgements of 3D shape when viewing these shapes, and find that the human visual system tempers its use of disparity signals depending on the structure of the adanaclastic surface. Second, we review neuroimaging work that identifies the neural circuits that process disparity to support depth perception. This work uses high-resolution fMRI combined with machine-learning analysis. In particular, we make parametric stimulus manipulations and test the degree to which different visual areas contain information about the viewed stimulus. This is quantified by the accuracy of a support vector machine in predicting the viewed stimulus from patterns of brain activity. We show that higher portions of both the dorsal and ventral visual pathways process perceptually-relevant disparity signals. However, the type of representation differs between pathways – dorsal responses relate to the metric depth structure, while ventral areas represent depth configurations (sign of depth rather than magnitude).nonotspecifiedhttp://www.cyberneum.de/published0Seeing in 3D: Human psychophysics, modelling and brain imaging1501715422Pretto2012_210PPrettoStadlerSvSGP20113WStadlerRISchubotzDYvon CramonASpringerMGrafWPrinz2011-05-00532677–687Human Brain Mappingany studies have shown the involvement of the premotor cortex in action observation, recognizing this region as the neural marker of action simulation (i.e., internal modeling on the basis of the observer's own motor repertoire). So far, however, we have remained unaware of how action simulation differs from more general action representation in terms of premotor activation. The present fMRI experiment is the first to demonstrate how premotor structures contribute to action simulation as opposed to other action-related cognitive tasks, such as maintaining action representations. Using similar stimuli, a prediction condition requiring internal simulation of transiently occluded actions was compared to three different action-related control tasks differing solely in task instructions. Results showed right pre-SMA activation as a correlate of maintaining action representations in general. Moreover, the prediction condition was most efficient in activating the left pre-SMA and left PMd. These results suggest that the conjoint activation of the pre-SMA and PMd reflects a core neural driver of action simulation.nonotspecifiedhttp://www.cyberneum.de/published-677Predicting and memorizing observed action: Differential premotor cortex involvement1501715422RuddleVMB20113RARuddleEVolkovaBMohlerHHBülthoff2011-05-00439686699Memory & CognitionTwo experiments investigated the effects of landmarks and body-based information on route knowledge. Participants made four out-and-back journeys along a route, guided only on the first outward trip and with feedback every time an error was made. Experiment 1 used 3-D virtual environments (VEs) with a desktop monitor display, and participants were provided with no supplementary landmarks, only global landmarks, only local landmarks, or both global and local landmarks. Local landmarks significantly reduced the number of errors that participants made, but global landmarks did not. Experiment 2 used a head-mounted display; here, participants who physically walked through the VE (translational and rotational body-based information) made 36% fewer errors than did participants who traveled by physically turning but changing position using a joystick. Overall, the experiments showed that participants were less sure of where to turn than which way, and journey direction interacted with sensory information to affect the number and types of errors participants made.nonotspecifiedhttp://www.cyberneum.de/published13The effect of landmark and body-based sensory information on route knowledge1501715422FranchiRSSB20117AFranchiPRobuffo GiordanoCSecchiHISonHHBülthoffShanghai, China2011-05-00898905IEEE International Conference on Robotics and Automation (ICRA 2011)In this paper, a novel distributed control strategy for teleoperating a fleet of Unmanned Aerial Vehicles (UAVs) is proposed. Using passivity based techniques, we allow the behavior of the UAVs to be as flexible as possible with arbitrary split and join decisions while guaranteeing stability of the system. Furthermore, the overall teleoperation system is also made passive and, therefore, characterized by a stable behavior both in free motion and when interacting with unknown passive obstacles. The performance of the system is validated through semi-experiments.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/2011a-FraRobSecSonBue-preprint.pdfpublished7A Passivity-Based Decentralized Approach for the Bilateral Teleoperation of a Group of UAVs with Switching Topology1501715422AlexandrovaRBKTBM20117IVAlexandrovaMRallMBreidtUKloosGTulliusHHBülthoffBJMohlerHangzhou, Zhejiang, China2011-05-009122011 Workshop on Digital Media and Digital Content Management (DMDCM)Medical training centers often provide various simulations for students and professionals. Their goal is not only to make trainees practice specific scenarios but also to help them effectively transfer the acquired skills to the real
world. Having in mind that virtual environments have already been acknowledged for their potential to improve the medical training process, we propose an approach for rapid generation
of animated medical scenarios, which can be used as an additional training tool that fits into the time frame of a semester training program.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/CASA-2011-Alexandrova.pdfpublished3Animations of Medical Training Scenarios in Immersive Virtual Environments1501715422NolanBWFBR2011_27HNolanJSButlerRWhelanJJFoxeHHBülthoffRBReillyCancun, Mexico2011-05-0053565th International IEEE/EMBS Conference on Neural Engineering (NER 2011)The neural processes underlying perception of motion are relatively unknown. In this study Electroencephalography (EEG) is used to investigate the neural responses to passive self-motion. A Stewart platform was employed to translate subjects forwards and backwards while high-density EEG data was recorded. Modern source modeling methods were combined with classical waveform and topographic analyses to determine the electrophysiological correlates of motion processing.nonotspecifiedhttp://www.cyberneum.de/published3Electrophysiological source analysis of passive self-motion1501715422DoddsMdSB20117TJDoddsBJMohlerSde la RosaSStreuberHHBülthoffVancouver, BC2011-05-00132135Workshop Embodied Interaction: Theory and Practice in HCI (CHI 2011)This paper outlines our recent research that is providing users with a 3D avatar representation, and in particular focuses on studies in which the avatar is self-animated in real time. We use full body motion tracking, so when participants move their hands and feet, these movements are mapped onto the avatar. In a recent study (Dodds et al., CASA 2010), we found that a self-animated avatar aided participants in a communication task in a head-mounted display immersive virtual environment (VE). From the perspective of communication, we discovered it was not only important for the person speaking to be self-animated, but also for the person listening to us. Further, we show the potential of immersive VEs for investigating embodied interaction, and highlight possibilities for future research.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/CHI-2011-Dodds.pdfpublished3Embodied Interaction in Immersive Virtual Environments with Real Time Self-animated Avatars1501715422LeeFRSB20117DLeeAFranchiPRobuffo GiordanoHISonHHBülthoffShanghai, China2011-05-0013411347IEEE International Conference on Robotics and Automation (ICRA 2011)We propose a novel haptic teleoperation control framework for multiple unmanned aerial vehicles (UAVs) over the Internet, consisting of the three control layers: 1) UAV control layer, where each UAV is abstracted by, and is controlled to follow the trajectory of, its own kinematic virtual point (VP); 2) VP control layer, which modulates each VP's motion according to the teleoperation commands and local artificial potentials (for inter-VP/VP-obstacle collision avoidance and inter-VP connectivity preservation); and 3) teleoperation layer, through which a remote human user can command all (or some) of the VPs' velocity while haptically perceiving the state of all (or some) of the UAVs over the Internet. Master-passivity/slave-stability and some asymptotic performance measures are proved. Semi-experiment results are presented to validate the theory.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/2011b-LeeFraRobSonBue-preprint.pdfpublished6Haptic Teleoperation of Multiple Unmanned Aerial Vehicles over the Internet1501715422MasoneRB20117CMasonePRobuffo GiordanoHHBülthoffShanghai, China2011-05-0049354942IEEE International Conference on Robotics and Automation (ICRA 2011)This paper describes the mechanical and control design of the new 7-DOF CyberMotion Simulator, a redundant industrial manipulator arm consisting of a standard 6-DOF anthropomorphic manipulator plus an actuated cabin attached to the end-effector. Contrarily to Stewart platforms, an industrial manipulator offers several advantages when used as motion simulator: larger motion envelope, higher dexterity, and possibility to realize any end-effector posture within the workspace. In addition to this, the new actuated cabin acts as an additional joint and provides the needed kinematic redundancy to cope with the robot actuator and joint range constraints, which in general can significantly deteriorate the desired motion cues the robot is reproducing. In particular, we will show that, by suitably exploiting the redundancy better results can be obtained in reproducing sustained acceleration cues, a relevant problem when implementing vehicle simulators.nonotspecifiedhttp://www.cyberneum.de/published7Mechanical design and control of the new 7-DOF CyberMotion simulator1501715422Masone201110CMasoneWallravenC201110CWallravenLChuangDavidSVE20117NDavidJSchultzKVogeleyAEngelSan Francisco, CA, USA2011-04-036418th Annual Meeting of the Cognitive Neuroscience Society (CNS 2011)A focus on social deficits in autism spectrum disorders (ASD) has, for a long time, obscured the existence of lower-level perceptual abnormalities, although the earliest
descriptions of autism included abnormalities in oculomotor behavior and visual attention. More recently, however, abnormalities in perception and attention have increasingly been discussed as influential factors in ASD-specific psychopathology. To this end, the perception of coherent motion in random-dot kinematograms, biological motion in
point-light walkers and agency in animated shapes have been investigated in ASD but their relationship remains a matter of debate. It also is unclear whether ASD-related deficits result from difficulties in global motion perception or in processing motion that contains socially relevant signals (e.g. a body and actions). We tested 18 individuals with highfunctioning autism and 16 age-, gender- and IQ-matched control participants, who performed three tasks on a continuum of motion cues and social complexity: (1) low-level translational motion that moved up or down, (2) complex motion of a single dot that moved in an animate or
inanimate way, (3) complex motion of two dots that interacted or not. None of these tasks contained objects with human shape and only the first task contained global motion. Participants with autism were selectively
impaired in detecting social interaction between two animated shapes (task 3), while low-level motion processing (task 1) and the detection of isolated agents (task 2) were preserved. These findings suggest a distinct social impairment in ASD in understanding interacting agents.nonotspecifiedhttp://www.cyberneum.de/published-64Individuals with Autism Show a Selective Deficit for the Understanding of Interacting Animated Objects150171542268493MBarnett-CowanRWFlemingMSinghHHBülthoff2011-04-004615PLoS ONEBackground
How does the brain estimate object stability? Objects fall over when the gravity-projected centre-of-mass lies outside the point or area of support. To estimate an object's stability visually, the brain must integrate information across the shape and compare its orientation to gravity. When observers lie on their sides, gravity is perceived as tilted toward body orientation, consistent with a representation of gravity derived from multisensory information. We exploited this to test whether vestibular and kinesthetic information affect this visual task or whether the brain estimates object stability solely from visual information.
Methodology/Principal Findings
In three body orientations, participants viewed images of objects close to a table edge. We measured the critical angle at which each object appeared equally likely to fall over or right itself. Perceived gravity was measured using the subjective visual vertical. The results show that the perceived critical angle was significantly biased in the same direction as the subjective visual vertical (i.e., towards the multisensory estimate of gravity).
Conclusions/Significance
Our results rule out a general explanation that the brain depends solely on visual heuristics and assumptions about object stability. Instead, they suggest that multisensory estimates of gravity govern the perceived stability of objects, resulting in objects appearing more stable than they are when the head is tilted in the same direction in which they fall.nonotspecifiedhttp://www.cyberneum.de/published4Perceived Object Stability Depends on Multisensory Estimates of Gravity1501715422DavidSVE2011_27NDavidJSchultzKVogeleyAEngelCambridge, UK2011-04-00The Social Brain Workshop 2011nonotspecifiedhttp://www.cyberneum.de/published0Individuals with autism are impaired in social animacy perception but not in lower-level animacy or coherent motion perception1501715422RobuffoGiordano201110PRobuffo GiordanoBulthoffN201110HHBülthoffFNieuwenhuizen66423HISon2011-03-00324242256International Journal of Computer Integrated ManufacturingSupervisory control theory, which was first proposed by Ramadge and Wonahm, is a well-suited control theory for the control of complex systems such as semiconductor manufacturing systems, automobile manufacturing systems, and chemical processes because these are better modelled by discrete event models than by differential or difference equation models at higher levels of abstraction. Moreover, decentralised supervisory control is an efficient method for large complex systems according to the divide-and-conquer principle. This article presents a solution and a design procedure of supervisory control problem for the case of decentralised control. We apply the proposed design procedure to an experimental miniature computer-integrated manufacturing (CIM) system. This article presents the design of fourteen modular supervisors and one high-level supervisor to control the experimental miniature CIM system. These supervisors are controllable, non-blocking, and non-conflicting. After the verification of the supervisors by simulation, the collision avoidance supervisors for automated guided vehicle system have been implemented to demonstrate their efficacy.nonotspecifiedhttp://www.cyberneum.de/published14Design and implementation of decentralised supervisory control for manufacturing system automation150171542269503FSoykaPRobuffo GiordanoKBeykirchHHBülthoff2011-03-00120995107Experimental Brain ResearchIn previous research, direction detection thresholds have been measured and successfully modeled by exposing participants to sinusoidal acceleration profiles of different durations. In this paper, we present measurements that reveal differences in thresholds depending not only on the duration of the profile, but also on the actual time course of the acceleration. The measurements are further explained by a model based on a transfer function, which is able to predict direction detection thresholds for all types of acceleration profiles. In order to quantify a participant’s ability to detect the direction of motion in the horizontal plane, a four-alternative forced-choice task was implemented. Three types of acceleration profiles (sinusoidal, trapezoidal and triangular) were tested for three different durations (1.5, 2.36 and 5.86 s). To the best of our knowledge, this is the first study which varies both quantities (profile and duration) in a systematic way within a single experiment. The lowest thresholds were found for trapezoidal profiles and the highest for triangular profiles. Simulations for frequencies lower than the ones actually measured predict a change from this behavior: Sinusoidal profiles are predicted to yield the highest thresholds at low frequencies. This qualitative prediction is only possible with a model that is able to predict thresholds for different types of acceleration profiles. Our modeling approach represents an important advancement, because it allows for a more general and accurate description of perceptual thresholds for simple and complex translational motions.nonotspecifiedhttp://www.cyberneum.de/published12Predicting direction detection thresholds for arbitrary translational acceleration profiles in the horizontal plane150171542270167MBreidtHHBülthoffCCurioSanta Barbara, CA, USA2011-03-00713719Ninth IEEE International Conference on Automatic Face & Gesture Recognition and Workshops (FG 2011)Rich face models already have a large impact on the fields of computer vision, perception research, as well as computer graphics and animation. Attributes such as descriptiveness, semantics, and intuitive control are desirable properties but hard to achieve. Towards the goal of building such high-quality face models, we present a 3D model-based analysis-by-synthesis approach that is able to parameterize 3D facial surfaces, and that can estimate the state of semantically meaningful components, even from noisy depth data such as that produced by Time-of-Flight (ToF) cameras or devices such as Microsoft Kinect. At the core, we present a specialized 3D morphable model (3DMM) for facial expression analysis and synthesis. In contrast to many other models, our model is derived from a large corpus of localized facial deformations that were recorded as 3D scans from multiple identities. This allows us to analyze unstructured dynamic 3D scan data using a modified Iterative Closest Point model fitting process, followed by a constrained Action Unit model regression, resulting in semantically meaningful facial deformation time courses. We demonstrate the generative capabilities of our 3DMMs for facial surface reconstruction on high and low quality surface data from a ToF camera. The analysis of simultaneous recordings of facial motion using passive stereo and noisy Time-of-Flight camera shows good agreement of the recovered facial semantics.nonotspecifiedhttp://www.cyberneum.de/published6Robust Semantic Analysis by Synthesis of 3D Facial Motion1501715422wallravenSMVP20117CWallravenMSchultzeBMohlerAVatakisKPastraSanta Barbara, CA, USA2011-03-00484491Ninth IEEE International Conference on Automatic Face & Gesture Recognition and Workshops (FG 2011)A good data corpus lies at the heart of progress in both perceptual/cognitive science and in computer vision. While there are a few datasets that deal with simple actions, creating a realistic corpus for complex, long action sequences that contains also human-human interactions has so far not been attempted to our knowledge. Here, we introduce such a corpus for (inter)action understanding that contains six everyday scenarios taking place in a kitchen / living-room setting. Each scenario was acted out several times by different pairs of actors and contains simple object interactions as well as spoken dialogue. In addition, each scenario was first recorded with several HD cameras and also with motion-capturing of the actors and several key objects. Having access to the motion capture data allows not only for kinematic analyses, but also allows for the production of realistic animations where all aspects of the scenario can be fully controlled. We also present results from a first series of perceptual experiments that show how humans are able to infer scenario classes, as well as individual actions and objects from computer animations of everyday situations. These results can serve as a benchmark for future computational approaches that begin to take on complex action understanding.nonotspecifiedhttp://www.cyberneum.de/published7The POETICON enacted scenario corpus: A tool for human and computational experiments on action understanding1501715422NethSEKBM20117CNethJLSoumanDEngelUKloosHHBülthoffBJMohlerSingapore2011-03-00151158IEEE Virtual Reality Conference (VR 2011)The aim of Redirected Walking (RDW) is to redirect a person along their path of travel in a Virtual Environment (VE) in order to increase the virtual space that can be explored in a given tracked area. Among other techniques, the user is redirected on a curved real-world path while visually walking straight in the VE (curvature gain). In this paper, we describe two experiments we conducted to test and extend RDW techniques. In Experiment 1, we measured the effect of walking speed on the detection threshold for curvature of the walking path. In a head-mounted display (HMD) VE, we found a decreased sensitivity for curvature for the slowest walking speed. When participants walked at 0.75 m/s, their detection threshold was approximately 0.1m-1 (radius of approximately 10m). In contrast, for faster walking speeds (>;1.0m/s), we found a significantly lower detection threshold of approximately 0.036m-1 (radius of approximately 27m). In Experiment 2, we implemented many well known redirection techniques into one dynamic RDW application. We integrated a large virtual city model and investigated RDW for free exploration. Further, we implemented a dynamic RDW controller which made use of the results from Experiment 1 by dynamically adjusting the applied curvature gain depending on the actual walking velocity of the user. In addition, we investigated the possible role of avatars to slow the users down or make them rotate their heads while exploring. Both the dynamic curvature gain controller and the avatar controller were evaluated in Experiment 2. We measured the average distance that was walked before reaching the boundaries of the tracked area. The mean walked distance was significantly larger in the condition where the dynamic gain controller was applied. This distance increased from approximately 15m for static gains to approximately 22m for dynamic gains. This did not come at the cost of an increase in simulator sickness. Applying the avatar cont roller did reveal an effect on walking distance or simulator sickness.nonotspecifiedhttp://www.cyberneum.de/fileadmin/user_upload/files/publications/2011/VR-2011-Neth.pdfpublished7Velocity-Dependent Dynamic Curvature Gain for Redirected Walking1501715422Curio201110CCurioBreidt201110MBreidt63133JXMaierMDi LucaUNoppeney2011-02-00137245256Journal of Experimental Psychology: Human Perception and PerformanceCombining information from the visual and auditory senses can greatly enhance intelligibility of natural speech. Integration of audiovisual speech signals is robust even when temporal offsets are present between the component signals. In the present study, we characterized the temporal integration window for speech and nonspeech stimuli with similar spectrotemporal structure to investigate to what extent humans have adapted to the specific characteristics of natural audiovisual speech. We manipulated spectrotemporal structure of the auditory signal, stimulus length, and task context. Results indicate that the temporal integration window is narrower and more asymmetric for speech than for nonspeech signals. When perceiving audiovisual speech, subjects tolerate visual leading asynchronies, but are nevertheless very sensitive to auditory leading asynchronies that are less likely to occur in natural speech. Thus, speech perception may be fine-tuned to the natural statistics of audiovisual speech, where facial movements always occur before acoustic speech articulation.nonotspecifiedhttp://www.cyberneum.de/published11Audiovisual asynchrony detection in human speech150171542215017188241501718826delaRosaCC20113Sde la RosaRNChoudheryAChatziastros2011-02-001373847Journal of Experimental Psychology: Human Perception and PerformanceRecent evidence suggests that the recognition of an object's presence and its explicit recognition are temporally closely related. Here we re-examined the time course (using a fine and a coarse temporal resolution) and the sensitivity of three possible component processes of visual object recognition. In particular, participants saw briefly presented (Experiment I to III) or noise masked (Experiment IV) static images of objects and non-object textures. Participants reported the presence of an object, its basic level category, and its subordinate category while we measured recognition performance by means of accuracy and reaction times. All three recognition tasks were clearly separable in terms of their time course and sensitivity. Finally, the use of a coarser temporal sampling of presentation times decreased performance differences between the detection and basic level categorization task suggesting that a fine temporal sampling for the dissociation of recognition performances is important. Overall the three probed recognition processes were associated with different time courses and sensitivities.nonotspecifiedhttp://www.cyberneum.de/published9Visual object detection, categorization, and identification tasks are associated with different time courses and sensitivities1501715422Soyka201110FSoykaAlexandrova201114IVAlexandrova2011-01-17nonotspecifiedpublishedGenerating Virtual Humans Using Predefined Bodily and Facial Emotions in Real-Time Immersive Virtual Environmentsmaster1501715422Bulthoff201110HHBülthoff67243AReichenbachKWhittingstallAThielscher2011-01-0025413751384NeuroimageTranscranial magnetic stimulation (TMS) can non-invasively modify cortical neural activity by means of a time-varying magnetic field. For example, in cognitive neuroscience, it is applied to create reversible virtual lesions in healthy humans (usually assessed as diminished performance in a behavioral task), thereby helping to establish causal structurefunction relationships. Despite its widespread use, it is still rather unclear how TMS acts on existing, task-related neural activity, potentially resulting in a measurable effect on the behavioral level. Here, we deliver TMS to early visual areas while recording EEG in order to directly characterize the interaction between TMS-evoked (TEPs) and visual-evoked potentials (VEPs). Simultaneously, the subjects&amp;lsquo; performance is assessed in a visual forced-choice task. This allows us to compare the TMS effects on the VEPs across different levels of behavioral impairment. By systematically varying the stimulation intensity, we demonstrate
tha
t TMS strongly enhances the overall visual stimulus-related activity (rather than disrupting it). This enhancement effect saturates when behavior is impaired. This might indicate that the neural coding of the visual stimulus is robust to noise within a certain dynamic range (as indexed by the enhancement). Strong disturbances might saturate this range, causing behavioral impairment. Variation of the timing between the visual stimulus and the magnetic pulse reveals a constructive interference between the TEPs and VEPs: The better the overlap between both evoked potentials, the stronger the interaction effect when TMS and visual stimulation are combined. Importantly, however, this effect is uncorrelated with the strength of behavioral impairment.nonotspecifiedhttp://www.cyberneum.de/published9Effects of transcranial magnetic stimulation on visual evoked potentials in a visual suppression task15017154221501715421150171882157463TStichCLinzCWallravenDWCunninghamMMagnor2011-01-0028128ACM Transactions on Applied PerceptionWe present a method for image interpolation that is able to create high-quality, perceptually convincing transitions between recorded images. By implementing concepts derived from human vision, the problem of a physically correct image interpolation is relaxed to that of image interpolation which is perceived as visually correct by human observers. We find that it suffices to focus on exact edge correspondences, homogeneous regions and coherent motion to compute convincing results. A user study confirms the visual quality of the proposed image interpolation approach. We show how each aspect of our approach increases perceived quality of the result. We compare the results to other methods and assess achievable quality for different types of scenes.nonotspecifiedhttp://www.cyberneum.de/published27Perception-Motivated interpolation of image sequences150171542264423LTcheangHHBülthoffNBurgess2011-01-00310811521157Proceedings of the National Academy of Sciences of the United States of AmericaOur ability to return to the start of a route recently performed in darkness is thought to reflect path integration of motion-related information. Here we provide evidence that motion-related interoceptive representations (proprioceptive, vestibular, and motor efference copy) combine with visual representations to form a single multimodal representation guiding navigation. We used immersive virtual reality to decouple visual input from motion-related interoception by manipulating the rotation or translation gain of the visual projection. First, participants walked an outbound path with both visual and interoceptive input, and returned to the start in darkness, demonstrating the influences of both visual and interoceptive information in a virtual reality environment. Next, participants adapted to visual rotation gains in the virtual environment, and then performed the path integration task entirely in darkness. Our findings were accurately predicted by a quantitative model in which visual and interoceptive inputs combine into a single multimodal representation guiding navigation, and are incompatible with a model of separate visual and interoceptive influences on action (in which path integration in darkness must rely solely on interoceptive representations). Overall, our findings suggest that a combined multimodal representation guides large-scale navigation, consistent with a role for visual imagery or a cognitive map.nonotspecifiedhttp://www.cyberneum.de/published5Visual influences on path integration in darkness indicates a multimodal representation of large-scale space150171542267813KSPilzQCVuongHHBülthoffIMThornton2011-01-0011181731CognitionA highly familiar type of movement occurs whenever a person walks towards you. In the present study, we investigated whether this type of motion has an effect on face processing. We took a range of different 3D head models and placed them on a single, identical 3D body model. The resulting figures were animated to approach the observer. In a first series of experiments, we used a sequential matching task to investigate how the motion of an approaching person affects immediate responses to faces. We compared observers responses following approach sequences to their performance with figures walking backwards (receding motion) or remaining still. Observers were significantly faster in responding to a target face that followed an approach sequence, compared to both receding and static primes. In a second series of experiments, we investigated long-term effects of motion using a delayed visual search paradigm. After studying moving or static avatars, observers searched for target faces in static arrays of varyin
g set sizes. Again, observers were faster at responding to faces that had been learned in the context of an approach sequence. Together these results suggest that the context of a moving body influences face processing, and support the hypothesis that our visual system has mechanisms that aid the encoding of behaviourally-relevant and familiar dynamic events.nonotspecifiedhttp://www.cyberneum.de/published14Walk this way: Approaching bodies can influence the processing of faces1501715422Armann20111RArmannLogos-VerlagBerlin, Germany2011-00-00Tübingen, Univ., Diss., 2011nonotspecifiedhttp://www.cyberneum.de/published167Faces in the Brain: a Behavioral, Eye-tracking and High-level Adaptation Approach to Human Face Perception1501715422Gaissert20111NGaissertLogos-VerlagBerlin, Germany2011-00-00Das wichtigste Werkzeug des Menschen sind seine Hände. Obwohl dieses Sprichwort schon sehr alt ist, ist nur wenig darüber bekannt, wie und was der Mensch wahrnimmt, wenn er Objekte in die Hand nimmt und betastet. Wie wird die ertastete Form eines Objektes im Gehirn abgespeichert? Ist die haptische Repräsentation ähnlich zu der, der visuellen Wahrnehmung? Entsteht sogar eine multisensorische, und somit gemeinsame, Repräsentation? Diese fundamentalen Fragen bilden den Hintergrund der vorliegenden Dissertation.
Die hier dargestellten Experimente zeigen, dass der Mensch sehr ähnliche perzeptuelle Räume generiert, wenn komplexe Formen eines parametrisch definierten Objektraumes visuell oder haptisch exploriert werden. Um dies zu zeigen, wurde zuerst ein dreidimensionaler Objektraum muschelähnlicher Objekte generiert, welche in drei Formparametern variieren. Versuchspersonen wurden in den visuellen Versuchen Fotos oder virtuelle Rekonstruktionen der Objekte gezeigt, während in den haptischen Versuchen 3D Plastikmodelle der Objekte, generiert mit einem 3D Drucker, mit verbundenen Augen betastet wurden. In einer ersten Reihe von Experimenten bewerteten die Versuchspersonen die Ähnlichkeit zweier, nacheinander gezeigter, Objekte.
Mit diesen Ähnlichkeitsbewertungen und mit Hilfe des Verfahrens der multidimensionalen Skalierung wurden die perzeptuellen Räume beider Modalitäten visualisiert. Überraschenderweise konnten die Versuchspersonen die Topologie des Objektraumes korrekt nachbilden, unabhängig davon, ob sie die Objekte gesehen oder betastet hatten. Weiterhin zeigten die Ergebnisse, dass der visuelle und der haptische perzeptuelle Raum fast identisch waren. Als nächstes wurden drei Kategorisierungsexperimente durchgeführt. Obwohl Kategorisierung allein durch den Tastsinn eher eine ungewöhnliche Aufgabe ist, konnte sie genauso gut gelöst werden, wie wenn die Versuchspersonen die Objekte sehen konnten. Anschließend wurden die perzeptuellen Räume beider Modalitäten mit den Ergebnissen der Kategorisierungsexperimente verglichen. Für alle Kategorisierungsexperimente und für beide Modalitäten war die wahrgenommene Ähnlichkeit zwischen Objekten einer Kategorie höher, als die Ähnlichkeit zweier Objekte aus unterschiedlichen Kategorien. Das heißt, dass, sowohl visuell als auch haptisch, Objekte in einer Kategorie zusammengruppiert wurden, die als sehr ähnlich wahrgenommen wurden.
Um zu untersuchen, inwieweit die auf den computergenerierten Objekten basierenden Ergebnisse auf natürliche Objekte übertragbar sind, wurde eine Sammlung von Muscheln und Salzwasserschnecken erstellt. Mit diesen wurden, wie oben beschrieben, Ähnlichkeitsbewertungen durchgeführt und mittels multidimensionaler Skalierung die perzeptuellen Räume visualisiert. Wiederum waren der visuelle und der haptische perzeptuelle Raum fast identisch. Interessanterweise konnte man in beiden Räumen eine Gruppenbildung erkennen, weshalb auch hier drei Kategorisierungsexperimente durchgeführt wurden. Obwohl die Muscheln in einer Vielzahl an Objektmerkmalen variierten, z.B. Form, Farbe, Muster etc., konnten die Versuchspersonen diese Aufgabe ohne Mühe lösen, auch wenn sie die Objekte nur betasten durften. Zusätzlich konnte die Gruppenbildung, die schon in den perzeptuellen Räumen erkennbar war, die Kategorisierungsergebnisse richtig vorhersagen.
Zusammengenommen weisen diese Ergebnisse darauf hin, dass die visuelle und die haptische Repräsentation von Objekten sehr eng miteinander verknüpft sein müssen. Zusätzlich liefern die Experimente Hinweise darauf, dass die gleichen Prozesse genutzt werden, wenn Ähnlichkeiten zwischen Objekten wahrgenommen werden, oder Objekte kategorisiert werden, egal ob die Objekte visuell oder haptisch exploriert werden.Tübingen, Univ., Diss., 2011nonotspecifiedhttp://www.cyberneum.de/published204Perceiving Complex Objects: A Comparison of the Visual and the Haptic Modalities1501715422LL20111ChuangLLLogos-VerlagBerlin, Germany2011-00-00Tübingen, Univ., Diss., 2011nonotspecifiedhttp://www.cyberneum.de/published162Recognizing Objects from Dynamic Visual Experiences1501715422Engel2011_21DEngelLogos-VerlagBerlin, Germany2011-00-00Computer vision aims to teach machines and algorithms to 'see' with the ultimate goal of creating 'intelligent' applications and devices that can provide assistance to humans in a wide array of scenarios. This thesis presents an investigation of computer vision on three layers: low-level features, mid-level representations and high-level applications. Each of the layers depends on the previous ones while also generating constraints and requirements for them. At the application layer human-machine interfaces come into play and link the human perception to computer vision. By studying all layers we can gain a much deeper insight into the interplay of different methods, than by examining an isolated problem. Furthermore, we are able to factor constraints imposed by different layers and the users into the design of the algorithms, instead of optimizing a single method based purely on algorithmic performance measures. After a brief introduction in Chapter 1, Chapter 2 addresses the feature layer and describes our novel shape-centered interest points that play a vital role throughout this thesis. These interest points are formed at location of high local symmetry as opposed to corner interest points which occur along the outline of shapes.
Experiments show that they are very robust with respect to common natural image transformations, such as scaling, rotation and the introduction of noise and clutter. Based on these features Chapter 3 presents two strategies to build robust mid-level image representations. First, a novel feature grouping method is introduced. The scheme offers a powerful way to combine the advantages of shape-centered interest points, namely robustness and a tight connection to a unique shape, and corner-based interest points, namely strong descriptors. Furthermore, Chapter 3 introduces a novel set of medial feature superpixels, that represent a feed-forward way to divide the image into small, visually-homogeneous regions offering a compact and efficient mid-level representation of the image information. Finally, Chapter 4 bridges the gap between computer vision and the human observer by introducing three applications that employ the shape-centered representations from the two previous Chapters. First a multi-class scene labeling scheme is presented that produces dense annotations of images, combining a local prediction step with a global optimization scheme. Then, Section 4.2 introduces a novel image retrieval tool that operates on highlevel semantic information. Such semantic annotations could be generated by automatic annotation schemes as the one described in the previous Section. Finally, the novel idea of predicting the detectability of a pedestrian in a driver assistance context is put forward and investigated. The different modules of this thesis are tightly connected and inter-dependent, in the framework of shape-centered representations. The connections between the modules avails the possibility to feed information back from higher to lower layers and optimize the design choices there. This thesis provides a framework looking at static phenomena but the presented approach could be extended to the analysis of dynamic scenes as well.Tübingen, Univ., Diss., 2011nonotspecifiedhttp://www.cyberneum.de/published173Shape-Centered Representations: From Features to Applications1501715422BulthoffCW20172HHBülthoffDWCunninghamCWallravenSpringerLondon, UK2011-00-00575596Handbook of Face RecognitionIn this chapter, we will focus on the role of motion in identity and expression recognition in human, and its developmental and neurophysiological aspects. Based on results from literature, we make it clear that there is some form of characteristic facial information that is only available over time, and that it plays an important role in the recognition of identity, expression, speech, and gender; and that the addition of dynamic information improves the recognizability of expressions and identity, and can compensate for the loss of static information. Moreover, at least several different types of motion seem to exist, they play different roles, and a simple rigid/nonrigid dichotomy is neither sufficient nor appropriate to describe these motions. Additional research is necessary to determine what the dynamic features for face processing are.nonotspecifiedhttp://www.cyberneum.de/published21Dynamic Aspects of Face Processing in Humans1501715422ErnstDM20112MErnstMDi LucaOxford University PressNew York, NY, USA2011-00-00225250Sensory Cue IntegrationThe brain receives information about the environment from all the sensory modalities, including vision, touch, and audition. To interact efficiently with the environment, this information must eventually converge to form a reliable and accurate multimodal percept. This process is often complicated by the existence of noise at every level of signal processing, which makes the sensory information derived from the world unreliable and inaccurate. There are several ways in which the nervous system may minimize the negative consequences of noise in terms of reliability and accuracy. Two key strategies are to combine redundant sensory estimates and to use prior knowledge. This chapter elaborates further on how these strategies may be used by the nervous system to obtain the best possible estimates from noisy signals.nonotspecifiedhttp://www.cyberneum.de/published25Multisensory perception: from integration to remapping15017154221501718824BarnettCowanSZGLd201146MBarnett-CowanFSoykaLZaichikEGroenWLedegangMde Mena2011-00-002011-00-00Analysis of perception data and motion perception criterianonotspecifiedAnalysis of perception data and motion perception criteria1501715422BeykirchBZBL201146KBeykirchMBarnett-CowanLZaichikJBosWLedegang2011-00-002011-00-00Development of add-on perception modelnonotspecifiedDevelopment of add-on perception model1501715422BeykirchSB201046MBeykirchFSoykaMBarnett-Cowan2011-00-002011-00-00Evaluation of the baseline perception models and required amendmentsnonotspecifiedEvaluation of the baseline perception models and required amendments1501715422Armann2011_215RArmann2011-00-00nonotspecifiedpublishedFaces in the Brain: a Behavioral, Eye-tracking and High-level Adaptation Approach to Human Face Perception1501715422Gaissert2011_215NGaissert2011-00-00nonotspecifiedpublishedPerceiving Complex Objects: A Comparison of the Visual and the Haptic Modalities1501715422Chuang2011_515LLChuang2011-00-00nonotspecifiedpublishedRecognizing Objects From Dynamic Visual Experiences1501715422Engel201115DEngel2011-00-00nonotspecifiedpublishedShape-Centered Representations: From Features to Applications1501715422RobuffoGiordano201010PRobuffo GiordanoMeilinger2010_210TMeilingerVitello20101MPVitelloLogos-VerlagBerlin, Germany2010-12-00The perception of motion is probably one of the major challenges to our sensory system. Motion perception is crucial during the tracking of moving objects (prey, predator etc.) and to maintain spatial orientation during locomotion. Moreover, it is typically a multisensory event. In everyday situations, the visual sense is supposed to provide the most accurate information since its spatial resolution is the most accurate among the senses. However, auditory and somatosensory supplements are aligned to vision and help to generate a more accurate percept of a given situation. Visual motion has been investigated intensively for many years. Compared to vision, auditory and tactile motion perceptions are far less understood. Today, it is still not understood if motion perception is a common feature, following the same principles among the senses and maybe processed within the same brain regions.Tübingen, Univ., Diss., 2010nonotspecifiedhttp://www.cyberneum.de/published124Perception of moving tactile stimuli1501715422150171882466883MBarnett-Cowan2010-12-00123916841686PerceptionEating is a multisensory experience involving more than simply the oral sensation of the taste and smell of foods. It has been shown that the way foods look, sound, and feel like in the mouth all affect food perception. The influence of haptic information available when handling food is relatively unknown. In this study, blindfolded participants bit-into fresh or stale pretzels while rating their freshness-staleness and crispness-softness. Information provided to the hand was either congruent (whole pretzel fresh or stale) or incongruent (half pretzel fresh, half stale) with what was presented to the mouth. The results demonstrate that the perception of both freshness and crispness were systematically altered when incongruent information was provided: bit-into fresh pretzel-tips were perceived as staler and softer when a stale pretzel-tip was held in the hand and vice versa. Haptic information available when handling food thus plays a significant role in modulating food perception.nonotspecifiedhttp://www.cyberneum.de/published2An illusion you can sink your teeth into: Haptic cues modulate the perceived freshness and crispness of pretzels150171542261283MDi Luca2010-12-00619569584PresenceA virtual reality (VR) system tracks one or more objects to generate the depiction of a virtual environment from the user's vantage point. No system achieves this instantaneously: changes in the depicted virtual environment are delayed from changes in the position of the objects being tracked. In this paper, a method is proposed to quantify this time difference, the end-to-end delay of the VR system. Two light-sensing devices and two luminance gradients are used to simultaneously encode the position of one tracked object and its virtual counterpart. One light-sensing device is attached to the tracked object and it captures light from the gradient in the physical environment. The other device captures light from the gradient in the virtual environment. A measurement is obtained by moving the tracked object repetitively (by hand) across the gradient. The end-to-end delay is the asynchrony between the signals generated by the two light-sensing devices. The results collected with oscillatory movements performed at different frequencies indicate that for some VR systems, the end-to-end delay might not be constant but could vary as a function of the oscillation frequency.nonotspecifiedhttp://www.cyberneum.de/published15New method to measure end-to-end delay of virtual reality15017154221501718824DeussenBEKLRS20103ODeussenHHBülthoffTErtlDKeimBLintermannHReitererASchilling2010-12-00633551558Informatik-SpektrumEntwicklungen in der Displaytechnologie haben in den vergangenen Jahren eine Vielzahl hochauflösender Bildschirme hervorgebracht. Der Forschungsverbund ,,Information at your finger tips – interaktive Visualisierung für Gigapixel Displays“ hat sich mit den Herausforderungen beschäftigt, die diese Technologie für viele Bereiche der Informatik in sich birgt. Hierbei wurden sowohl neue Grafiksysteme untersucht als auch Interaktionsmethoden und Darstellungsformen sowie deren Anwendung in Visualisierung und Kunst.nonotspecifiedhttp://www.cyberneum.de/published7Visualisierung auf Großbildschirmen: Herausforderung eines neuen Ausgabegeräts150171542269967MBreidtHHBülthoffCCurioSeoul, Korea2010-12-00123rd ACM SIGGRAPH Conference and Exhibition on Computer Graphics and Interactive Techniques in Asia (SIGGRAPH Asia 2010)Affordable 3D vision is just about to enter the mass market for consumer products such as video game consoles or TV sets. Having depth information in this context is beneficial for segmentation as well as gaining robustness against illumination effects, both of which are hard problems when dealing with color camera data in typical living room situations. Several techniques compute 3D (or rather 2.5D) depth information from camera data such as realtime stereo, time-of-flight (TOF), or real-time structured light, but all produce noisy depth data at fairly low resolutions. Not surprisingly, most applications are currently limited to basic gesture recognition using the full body. In particular, TOF cameras are a relatively new and promising technology for compact, simple and fast 2.5D depth measurements. Due to the measurement principle of measuring the flight time of infrared light as it bounces off the subject, these devices have comparatively low image resolution (176 x 144 ... 320 x 240 pixels) with a high le
vel of noise present in the raw data.nonotspecifiedhttp://www.cyberneum.de/published-12Face Models from Noisy 3D Cameras150171542268207RMcDonnellMBreidtSeoul, Korea2010-12-00413rd ACM SIGGRAPH Conference and Exhibition on Computer Graphics and Interactive Techniques in Asia (SIGGRAPH Asia 2010)The Uncanny Valley (UV) has become a standard term for the theory that near-photorealistic virtual humans often appear unintentionally erie or creepy. This UV theory was first hypothesized by robotics professor Masahiro Mori in the 1970&lsquo;s [Mori 1970] but is still taken seriously today by movie and game developers as it can stop audiences feeling emotionally engaged in their stories or games. It has been speculated that this is due to audiences feeling a lack of empathy towards the characters. With the increase in popularity of interactive drama video games (such as L.A. Noire or Heavy Rain), delivering realistic conversing virtual characters has now become very important in the real-time domain. Video game rendering techniques have advanced to a very high quality; however, most games still use linear blend skinning due to the speed of computation. This causes a mismatch between the realism of the appearance and animation, which can result in an uncanny character. Many game developers opt
for a stylised rendering (such as cel-shading) to avoid the uncanny effect [Thompson 2004]. In this preliminary work, we begin to study the complex interaction between rendering style and perceived trust, in order to provide guidelines for developers for creating plausible virtual characters.nonotspecifiedhttp://www.cyberneum.de//fileadmin/user_upload/files/publications/SiggraphAsia2010-McDonnell_6820[0].pdfpublished-41Face Reality: Investigating the Uncanny Valley for virtual faces150171542266767FPasqualettiAFranchiFBulloAtlanta, GA, USA2010-12-007153715849th IEEE Conference on Decision and Control (CDC 2010)This work considers the problem of designing optimal multi-agent trajectories to patrol an environment. As performance criterion for optimal patrolling we consider the worst-case time gap between any two visits of the same region. We represent the area to be patrolled with a graph, and we characterize the computational complexity of the trajectory design (patrolling) problem with respect to the environment topology and to the number of robots employed in the patrolling task. Even though the patrolling problem is generally NP-hard, we identify particular cases that are solvable efficiently, and we describe optimal patrolling trajectories. Finally, we present a heuristic with performance guarantees, and an 8-approximation algorithm to solve the NP-hard patrolling problem.nonotspecifiedhttp://www.cyberneum.de//fileadmin/user_upload/files/publications/0819_6676[1].pdfpublished5On optimal cooperative patrolling150171542266757AFranchiPStegagnoGOrioloAtlanta, GA, USA2010-12-006534654049th IEEE Conference on Decision and Control (CDC 2010)Recent research on multi-agent systems has produced
a plethora of decentralized controllers that implicitly
assume various degrees of agent localization. However, many
practical arrangements commonly taken to allow and achieve
localization imply some form of centralization, from the use of physical tagging to allow the identification of the single agent to the adoption of global positioning systems based on cameras or GPS. These devices clearly decrease the system autonomy and range of applicability, and should be avoided if possible. Following this guideline, this work addresses the mutual localization problem with anonymous relative position measures, presenting a robust solution based on a probabilistic framework. The proposed localization system exhibits higher accuracy and lower
complexity (O(n2)) than our previous method [1]. Moreover,
with respect to more conventional solutions that could be
conceived on the basis of the current literature, our method
is theoretically suitable for tasks requiring frequent, manyto-many encounters among agents (e.g., formation control,